THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 


MARS   AS   THE   ABODE   OF   LIFE 


THE  MACMILLAN  COMPANY 

NEW  YORK    •    BOSTON   •    CHICAGO 
ATLANTA  •    SAN  FRANCISCO 

MACMILLAN  &  CO.,  LIMITED 

LONDON  •    BOMBAY  •    CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  LTD. 

TORONTO 


MARS 

AS 

THE    ABODE    OF    LIFE 


BY 


PERCIVAL    LOWELL,  A.B.,  LL.D. 

AUTHOR    OF    "MARS    AND    ITS    CANALS,"     ETC. 

DIRECTOR  OF  THE  OBSERVATORY  AT  FLAGSTAFF,   ARIZONA;    NON-RESIDENT  PROFESSOR 
OF  ASTRONOMY  AT  THE  MASSACHUSETTS   INSTITUTE  OF  TECHNOLOGY;    FELLOW  OF 
THE   AMERICAN   ACADEMY    OF   ARTS    AND    SCIENCES!     MEMBRE    DE    LA    SOCIETE 
ASTRONOMIQUE  DE  FRANCE;     MEMBER   OF  THE  ASTRONOMICAL  AND  ASTRO- 
PHYSICAL  SOCIETY   OF  AMERICA;    MITGLIED   DER   ASTRONOMISCHE  GE- 
SELLSCHAFT;     MEMBRE    DE    LA    sociETfi    BELGE    D'ASTRONOMIE; 

HONORARY    MEMBER   OF   THE    SOCIEDAD    ASTRONOMICA    DE    MEX- 
ICO;   JANSSEN    MEDALIST  OF   THE   SOCIET&   ASTRONOMIQUE   DB 
FRANCE,    1904,    FOR     RESEARCHES    ON     MARS;      ETC.,     ETC. 


ILLUSTRATED 


THE    MACMILLAN    COMPANY 

1908 

jdll  rights  reserved 


COPYRIGHT,  1908, 
Bv  THE  MACMILLAN  COMPANY. 

Set  up  and  electrotyped.     Published  December,  1908. 


Xcrfaoofi  tfrws 

J.  8.  Gushing  Co.  — Berwick  &  Smith  Co. 
Norwood,  Mass.,  U.S.A. 


Engineering  8 

Mathematical 

Science 

«fe 


ICo 

MY    BROTHER 

PROFESSOR   ABBOTT   LAWRENCE   LOWELL,    LL.D. 

WHO    AS    TRUSTEE    OF    THE    LOWELL    INSTITUTE 

PROPOSED    THESE    LECTURES 

THIS    PRESENTATION    OF    THEM 

IS    AFFECTIONATELY 

INSCRIBED 


PREFACE 

IN  1906  Professor  Lowell  was  asked  by  the  trustee 
of  the  Lowell  Institute  to  deliver  a  course  of  lectures 
there  upon  the  planet  Mars.  Eleven  years  had  elapsed 
since,  at  the  invitation  of  the  former  trustee,  he  had 
done  the  like.  When  the  time  came  for  their  delivery 
unusual  interest  was  manifested,  the  course  proving 
the  most  thronged  of  any  ever  given  before  the  Insti- 
tute. So  great  was  the  demand  for  seats  that  the  hall 
could  not  contain  the  crowd,  and  the  lectures  had  to 
be  repeated  in  the  afternoons,  to  audiences  almost  as 
large. 

The  eight  lectures  were  then  published,  with  slight 
changes,  in  six  papers  in  the  Century  Magazine,  and 
were  subsequently  wanted  by  Macmillan  and  Com- 
pany for  issuance  in  book  form. 

Though  dealing  specifically  with  Mars,  the  theme 
of  the  lectures  was  that  of  planetary  evolution  in  gen- 
eral, and  this  book  is  thus  a  presentation  of  something 
which  Professor  Lowell  has  long  had  in  mind  and  of 
which  his  studies  of  Mars  form  but  a  part,  the  re- 
search into  the  genesis  and  development  of  what  we 
call  a  world ;  not  the  mere  aggregating  of  matter,  but 


viii  PREFACE 

what  that  aggregation  inevitably  brings  forth.  The 
subject  which  links  the  Nebular  Hypothesis  to  the 
Darwinian  theory,  bridging  the  evolutionary  gap  be- 
tween the  two,  he  has  called  planetology,  thus  desig- 
nating the  history  of  the  planet's  individual  career. 
It  is  in  this  light  that  Mars  is  here  regarded :  how  it 
came  to  be  what  it  is  and  how  it  came  to  differ  from 
the  Earth  in  the  process. 

The  object  of  the  founding  of  the  Observatory  at 
Flagstaff  was  the  study  of  the  planets  of  our  solar 
system  ;  a  subject  it  has  now  for  fourteen  years  made 
its  specialty,  the  site,  chosen  for  the  purpose,  en- 
abling it  to  prosecute  this  study  to  more  advantage 
than  is  possible  at  any  other  observatory  at  present. 
From  the  data  thus  collected,  light  has  been  thrown 
upon  the  evolution  of  the  planets  as  worlds,  resulting 
in  a  thesis  of  which  the  present  book  is  a  preliminary 
presentation. 

As  in  all  theses,  the  cogency  of  the  conclusion  hangs 
upon  the  validity  of  each  step  in  the  argument.  It  is 
vital  that  each  of  these  should  be  based  on  all  that 
we  know  of  natural  laws  and  the  general  principles 
underlying  them.  Their  truth  can  only  be  adequately 
appreciated  by  those  able  to  follow  the  physical  and 
mathematical  processes  involved,  and  for  this  the  gen- 
eral reader  has  not  the  necessary  technical  education. 
Yet  there  are  many,  professional  and  unprofessional 


PREFACE  ix 

alike,  capable  of  comprehending  provided  the  steps 
are  made  sufficiently  explicit.  It  has  seemed,  there- 
fore, worth  the  trying  to  attempt  to  write  for  both 
classes  of  the  community  in  a  single  volume.  To  do 
this,  the  general  text  has  been  printed  complete  in 
itself,  while  the  demonstrations  of  the  several  steps 
have  been  collected  in  a  part  by  themselves  with  refer- 
ence to  the  places  in  the  text  where  they  severally 
should  occur.  All  illustrations  of  the  planet  Mars 
are  by  Professor  Lowell. 

MAY,   1908. 


CONTENTS 


PAGE 

FOREWORD      .........          i 

PART   I 

c* 


I.     THE  GENESIS  OF  A  WORLD         .....          3 

Catastrophic  origin        ......          3 

Meteorites  .......          4 

Meteorite  worship        ......          4 

Meteoric  constitution  of  solar  system         ...          5 
Analogy  of  cataclysm  to  new  stars  (Novae)       .          .          6 
The  meteorites  gravitate  together,  generating  heat         .          6 
Amount  of  heat  depends  on  the  mass  of  the  body         .          7 
Substances  vary  with  heat  and  pressure      ...          8 
Mass  the  fundamental  factor  .....          9 

Cooling     ........          9 

Life-history  depends  on  size  .          .          .          .          .11 

Planetologic  eras  .          .          .          .          .  1 1 

Present  aspects  of  the  planets  our  guide     .  .          .12 

Geologic  part  of  planetology  .          .          .          .  13 

Landscape  the  result  of  cooling         .          .          .          .14 

Mountains  in  proportion  to  mass      .  .          .  1 5 

Volcanic  phenomena     .          .          .          .          .          .16 

Relative  roughness  of  Earth,  Moon,  and  Mars  .          .        16 
Mountains  absent  on  Mars     .          .          .          .          .16 

Slant  illumination          .          .          .          .          .          .17 

Importance  to  astronomers      .          .          .          .          .17 

Applied  to  Mars  .          .          .          .          .          .18 

Not  indicative  of  mountains   .          .          .  .          .21 

Two  or  three  thousand  feet  limit  of  elevation  on  Mars         22 


xii  CONTENTS 

CHAPTER  PAGE 

Internal  heat  of  the  three  bodies      .          ,          .  .23 

Darwinian  theory  of  lunar  origin      .          .          .  26 
Confirmed  by  lunar  surface    .          . .        .          ...        26 

Probable  comparative  internal  heat  of  earth  and  Mars  .        27 

Continental  and  oceanic  areas  formed        .          .  .28 

Their  distribution  determined           .          .          .  .28 

True  Martian  message            .          .          .          .  30 

Their  relative  size  on  different  planets       .          .  .30 

Earth's  oceanic  basins  permanent     .          .          .  .32 

Their  flooring  attests  it      •     .          .          .          .  -33 

II.     THE  EVOLUTION  OF  LIFE          .          .         .         .  -35 

The  origin  of  organic  life        .          .                    .  •        3  5 

Life  an  inevitable  phase  of  planetary  evolution     .  .        37 

Water  essential  to  life   .          .          .          .          .  -39 

Seas  the  earliest  home  of  mundane  life       .          .  .42 

Uniformity  of  paleozoic  fossils          .          .          .  .        45 

Carboniferous  plant  life  .....        46 

Light  less  and  heat. more  then  than  now   .          .  .        48 

Effect  on  the  earth        .          .          .        •'.'."  .        49 

Earth  itself  responsible  for  paleozoic  heat  .          .  .50 

Earth,  not  sun,  the  motive  force  in  evolution  in  the 

paleozoic  era  .          .          .          .          .          .  .        52 

A  once  cloudy  Mars     .          .          .          .          .  .52 

Life  outgrows  the  sea    .          .          .          .          .  -53 

Effect  of  environment  upon  evolution        .          .  .54 

Deep-sea  life  thought  impossible  fifty  years  ago  .  .        57 

Extinction  of  light        .          .          .          .          .  -57 

Deep-sea  life        .          .          .          .          .          .  .58 

Blindness  ........       60 

Phosphorescent  organs  .          .          .          .          .  .61 

Lesson  of  the  fishing  fishes     .          .          .          .  .61 

Cosmic  character  of  life          .....        64 

III.      THE  SUN  DOMINANT        .          .          .          .          .  .        70 

Transition            .          .          .          .          .       "  ,  .70 


CONTENTS  xiii 

CHAPTER  PAGE 

The  sun  asserts  itself    .          .          .          .  .  .71 

Mars  betrays  the  same  evolution      .          .  .  -73 

The  thin  atmosphere  of  Mars           .          .  .  .78 

The  polar  caps  of  Mars          .          .          .  .  .80 

The  question  of  temperature  on  Mars       .  .  -83 

The  dear  skies  of  Mars          .          .          .  .  '85 

Summer  and  winter  temperatures     .          .  .  .87 

Aspect  of  Mars  corroborative           .          .  .  .89 

Summer  the  life  season  .....        90 

Zones  of  vegetation  of  the  San  Francisco  Mountains  .        93 

Summer  temperature  determinative  of  life  .  .  .        95 

Plateaux  hotter  than  peaks  at  a  like  elevation  .  .        98 

Water-vapor  in  the  air  of  Mars        .          ,  .      .  ,103 

Vegetation  of  Mars       .          .          .          .  .106 

Mode  of  manifestation  of  life            .          .  .  .107 

IV.   MARS  AND  THE  FUTURE  OF  THE  EARTH   .  *  .   1 1 1 

Mars  has  lost  its  oceans          .          .          .  .  .112 

The  oceans  of  earth  are  disappearing         .  .  .      1 1 8 

Gain  of  land  in  North  America  and  Europe  .  .      119 

Lowering  of  the  sea-level       .          .          .  .  .121 

Inland  seas          .          .          .          .          .  .  .121 

Terrestriality  succeeds  terraqueousness       .  .  .      123 

Deserts      .          .          .          .          .          .  .  .124 

The  petrified  forest  of  Arizona         .          .  .  .126 

Egypt  and  Carthage      .          .          .          .  ,  .      128 

Palestine    .          .          .          .          .          .  .  .129 

Subtropical  regions  chiefly  affected  .          .  .  .      129 

Planetary  change  far  advanced  on  Mars     .  .  .      131 

The  opaline  tints  of  Mars       .          .          .  .  .134 

How  the  earth  will  follow  Mars      .          .  .  .      135 

Water  present  in  the  Martian  atmosphere  .  .136 

The  surface  of  Mars  a  waterless  world      .  .  .142 

A  high  type  of  life  probable  on  Mars        .  .  .142^ 

The  probability  of  life  on  Mars  at  the  present  time  .      144    ,•' 


xiv  CONTENTS 

CHAPTER  PAGE 

V.     THE  CANALS  AND  OASES  OF  MARS     .  .  .  .146 

Schiaparelli  and  the  canals      .          .  .  ...      146 

Lines  are  straight           .          .          .  .  .  .148 

Canals  in  dark  regions  .           .           .  .  .  .152 

Canals  superposed  over  main  features  .  .  1 5  5 

Oases         .          .          .          .          .  .  .  .156 

Width  differs  for  different  doubles   .  .  .  1 60 

Area  of  zones      .          .          .          .  .  .  .163 

The  canals  are  subject  to  change      .  .  .  .167 

New  method  of  research         .          .  .  .  .168 

Search  for  clew  to  decipherment      .  .  .  .      1 74 

Quickening  of  canals  according  to  latitude  .  .      175 

Quickening  starts  at  polar  cap          .  .  .  .176 

The  earth  as  witnessed  from  space  .  .  .  .178 

Melting  first  necessary  on  Mars       .  .  .  .179 

Speed  of  spread  of  vegetation            .  .  .  .181 

VI.      PROOFS  OF  LIFE  ON  MARS         .          .  .  .  .184 

Discovery  of  celestial  truths  similar  to  detective  work  .      184 

Review  of  the  natural  chain  of  evidence  .  .  .186 

Aspect  of  Mars   corroborates   principles   of  planetary 

evolution         .          .          .          .  .  .  .186 

Animal  life  disclosed  only  by  mind  .  .  .      188 

Canals  confront  the  observer  .          .  .  .  .188 

Not  rivers            .          .          .          .  .  .  .191 

Not  cracks           .          .          .          .  .  .  .191 

Other  natural  explanations  prove  impossible  .  .      192 

Oases  equally  inexplicable      .                  .  .  .  .194 

Artificiality  suggests  itself       ...  .  .  195 

Great-circle  character  of  the  canals  .  .  .  .196 

Circularity  of  oases       .          .          .  .  .  *  .197 

Note  of  water  runs  through  the  action  .  .    -  .      197 

Its  locomotion  explained         .     .-«  .  .  .      199 

Mars'  surface  a  level  surface  .          .  .  .  .200 

Gravity  incapable  of  water  transference  .  .    -  .      201 

Organisms  evolve  as  a  planet  ages    .  .  .  .205 


CONTENTS  xv 


PAGE 


One  species  supplants  all  others  .  .  .  .      206 

To  die  of  thirst  .          .          .  .  ,  .  .      207 

End  foreseen        .......      208 

Further  phenomena       .          .  .  .  .  .211 

Speculation  excluded     .          .  .  .  .  .214 

Our  life  not  unique       .          .  .  .  .  .215 

Martian  life  nearing  its  end    .  .  .  .  .216 

PART   II 

NOTES 

1 .  On  Moment  of  Momentum          .          .          .          .  .219 

2.  The  Connection  of  Meteorites  with  the  Solar  System  .      220 

3.  The  Heat  developed  by  Planetary  Contraction          .  .225 

4.  The  Heights  of  Mountains  on  the  Moon         .          .  .     229 

5.  Heat  acquired  by  the  Moon         .          .          .          .  .    '230 

6.  Surface  Heat  of  Mars                    .          .          .          .  .231 

7.  The  Boiling-point  of  Water  on  Mars     .          .          .  .231 

8.  The  Paleozoic  Sun    .          .          .          .          .          .  .232 

9.  Effect  on  the  Earth  of  the  Supposed  Paleozoic  Sun  .  233 

10.  On  the  Influence  upon  the  Climate  of  Carbon  Dioxide  in 

the  Air        ........      236 

11.  Atmosphere  of  Mars  ......      238 

12.  The  Mean  Temperature  of  Mars  .          .          .          .240 

13.  A  Dust  Storm  on  Mars       ......      256 

14.  Mars  on  the  Cause  of  an  Ice-age  .          .          .          .265 

15.  Tidal  Effects 270 

1 6.  On  the  Visibility  of  Fine  Lines 271 

17.  Canals  of  Mars 279 

1 8.  Position  of  the  Axis  of  Mars        .          .          .          .          .280 

INDEX   .          .  283 


LIST   OF    ILLUSTRATIONS 

PLATES 

I.      On  the  Road  to  the  Observatory       .          .          .   Frontispiece 

OPPOSITE   PAGE 

II.      Mars — 1905       .......        74 

III.  Spectrogram  of  Moon  and  Mars   showing  the  Water- 

vapor  Band        .          .          .          .          .          .          .138 

IV.  Two  Photographs  of  London  taken  from  a  Balloon         .      148 
V.      At  the  Telescope  —  Observing  Artificial  Planets  .      172 

VI.     The  Lowell  Observatory  in  Mexico  .          .          .208 

VII.      Mars  in  1905       .          .          .          .          .          .          .217 

VIII.     A  Chinese  Translation  of  Lowell's  "Mars"       .          .      282 


CUTS   APPEARING   IN   TEXT 

PAGE 

Morehouse  Comet  ........          7 

Meteorite  from  Canon  Diablo,  Arizona  (pitted  by  fusion)          .         10 
Meteorite  from  Canon  Diablo,  Arizona  (surface  polished)          .         n 
Cloud  Effect  on  Jupiter     .          .          .          .          .          .          .12 

An  Apple  shrunk  to  show  the  Effect  of  Contraction          .  .        15 

Phase  View  of  the  Moon,  Mountainous  Surface  on  the  Termi- 
nator     .          .          .          .          .          .          .          .          .19 

Phase  View  of  Mars,  May,  1907        .....        20 

View  of  the  Earth  for  Proportion  of  Land  and  Sea  .          .        21 

Dust  Storm  on  Mars          .          .  .          .          .          .          .22 

Two  Views  of  the  Earth  as  seen  from  Space  .          .          .22 

Two  Views  of  Mars  for  Comparison  with  the  Earth        .          .        23 
A  Part  of  the  Moon's  Face  showing  Ancient  Sea-bottoms  .        26 

View  of  Mars  apportioning  Dark  and  Light  Areas  ...        29 
View  of  the  Moon  at  the  Full,  in  Like  Manner      .          .  3  i 

zvii 


xviii          LIST  OF  ILLUSTRATIONS 

PAGE 

Model  of  a  Brontosaurus   .          .          .          .          .          •   .       •        3  5 

Plant  Life  in  the  Coal  Measures  —  from  a  Fossil  Specimen         .        36 
Plant  Life  of  the  Upper  Devonian  —  from  a  Fossil  Specimen     .        3  8 
A  Trilobite     .........        40 

Fossil  Footprints  of  Amphibia     .          .          .          .          .          .41 

Deep-sea  Fishes ;    Challenger  Expedition       .  .  .  .42 

Deep-sea  Fish  ;    Challenger  Expedition          .          .          .  59 

Deep-sea  Angler  Fish ;    Challenger  Expedition       .          .          .62 
Deep-sea  Fish ;    Challenger  Expedition         .          .          .          .63 

Two  Views  of  the  Solis  Lacus  Region  on  Mars,  One  Hour  Apart        76 
The  North  Polar  Cap  of  Mars  at  its  Least  Extent  ...        79 
The  South  Polar  Cap  of  Mars  at  its  Greatest  Extent        .          .        80 
Drawing  of  Mars  with  Dark  Belt  girdling  Snow  during  its  Melting        8 1 
Early  Winter  Snow  Storm  in  the  Northern  Hemisphere  of  Mars        82 
Merriam's  Map  of  the  San  Francisco  Mountain  and  Vicinity      .        91 
The  San  Francisco  Peaks  .          .          .          .          .          .          .        92 

Arizona  Desert  View         .          .          •       ~-  .   •       .          .    '  93 

The  Douglas  Fir  .          .          .          .          .          .          -94 

Vertical  Distribution  of  Climate  on  Mountains,  showing  how 

Land-masses  raise  Temperature  .  .  *  .  .98 
Diagrammatic  Profile  of  the  San  Francisco  and  O'Leary  Peaks 

from  Southwest  to  Northeast  .  .  .*.  .  .99 
Chart  of  Effect  of  Plateau  on  Tree  Zones  —  Less  Elevation  .  i  oo 
Chart  of  Effect  of  Plateau  on  Tree  Zones  —  Greater  Elevation  i  o  i 
Diagrams  of  Two  Craters  with  Axis  of  Greatest  Cold  N.N.W.  102 
Comparative  Sizes  of  the  Earth  and  Mars  with  the  Polar  Caps 

of  Both  in  their  Springtime  •  ,  ••  .  •  .  1 1 1 

Lines  in  the  Dark  Areas  of  Mars,  proving  that  the  Latter  are 

not  Seas  .  . 115 

Two  Views  of  Mars  with  Parings  on  the  Terminator  .  .116 

Map  of  North  America,  showing  approximately  the  Area  of  Dry 

Land  at  the  Close  of  Archaean  Time     .          .          .          .119 

Petrified  Forest  of  Arizona  .          .          .          .          .          .125 

Another  View  of  the  Petrified  Forest  of  Arizona  .  .  .126 

Effect  of  the  Spring  Mist  around  the  North  Polar  Cap  of  Mars  i  36 


LIST  OF   ILLUSTRATIONS  xix 

PAGE 

A  Section  of  the  Canal  Eumenides-Orcus  terminating  in  the 

Junction  Trivium  Charontis  .  .  .  .  .150 
Canals  in  Dark  Regions  connecting  with  the  Polar  Cap  .  .  153 
Camera  of  the  Lowell  Observatory  by  which  the  Canals  of  Mars 

were  Photographed    .          .          .          .          .          .          .154 

Ascraeus  Lucus,  from  which  radiate  Many  Canals  .          .          .156 
Single  and  Double  Canals  .          .          .          .          .          .160 

A  Mass  of  Double  Canals  .          .          .          .          .          .160 

A  Mass  of  Single  Canals  about  Lucus  Phoenicis  .  .  .161 
Cartouche  of  the  Ceraunius  —  from  a  Chart  by  Lowell  .  .  174 
Time  of  Vegetation  on  the  Earth  —  from  a  Chart  by  Lowell  .  1 80 
Sprouting  Time  of  Vegetation  on  Mars  —  from  a  Chart  by  Lowell  182 
Luci  Ismenii,  revealing  the  Systematic  Method  in  which  the 

Double  Canals  enter  the  Twin  Oases  .  .  .  .190 
The  Moon,  showing  the  Straight  Wall  and  Rill  to  Right  of  Birt 

—  from  a  Drawing  by  Lowell,  May,  1905  .  .  .  191 
Mercury  —  Drawings  depicting  the  Irregular  Character  of  the 

Lines  on  the  Planet  differing  entirely  in  Look  from  those  on 

Mars       .          .          .          .          .          .          .          .  193 

A  Corner  of  Mars,  June  10,  1907       .          .          .          .  195 

Arethusa  Lucus,  April  15,  1903,  with  Converging  Canals  from 

the  North  Polar  Cap  .          .          .          .          .          .196 

Canals  from  the  South  Polar  Cap  of  Mars     .          .          .          .197 

Djihoun  .........      203 

Differentiation  of  the  Ganges      ......      205 

Northeast  Corner  of  Aeria,  July  2-5,  1907.          .          .          .      209 

The  Carets  of  Mars  .  .  .  •  .  ,  .  .212 

Mouths  of  Euphrates  and  Phison  .  .  .  .  .213 


PART    I 
PLANETOLOGY 


MARS   AS  THE  ABODE 
OF   LIFE 

FOREWORD 

UP  to  the  middle  of  the  nineteenth  century,  astron- 
omy was  busied  with  motions.  The  wanderings 
of  the  planets  in  their  courses  attracted  attention,  and 
held  thought  to  the  practical  exclusion  of  all  else  con- 
cerning them.  It  was  to  problems  of  this  character 
that  the  great  names  of  the  past  —  Newton,  Huygens, 
Laplace  —  were  linked.  But  when  the  century  that 
has  gone  was  halfway  through  its  course,  a  change 
came  over  the  spirit  of  the  investigation;  with  the 
advance  in  physics  celestial  searchers  began  to  con- 
cern themselves  with  matter,  too.  Gravitational  as- 
tronomy had  regarded  the  planets  from  the  point  of 
view  of  how  they  act;  physical  astronomy  is  intent 
upon  what  they  are. 

One  outcome  of  this  more  intimate  acquaintance 
is  the  new  study  with  which  the  present  papers  deal : 
the  evolution  of  the  planets  regarded  as  worlds.  Such 
research  has  to  do  not  merely  with  the  aggregation 
of  material,  but  with  its  subsequent  metamorphoses 


2  MARS   AS  THE   ABODE   OF   LIFE 

after  it  has  come  together.  Planetology  we  may  call 
this  science  of  the  making  of  worlds,  since  it  concerns 
itself  with  the  life-history  of  planetary  bodies  from 
their  chemically  inert  beginning  to  their  final  inert 
end.  It  constitutes  the  connecting  link  in  the  long 
chain  of  evolution  from  nebular  hypotheses  to  the 
Darwinian  theory.  It  is  itself  neither  the  one  nor 
the  other,  but  takes  up  the  tale  where  the  one  leaves 
off,  and  leaves  it  for  the  other  to  continue. 


CHAPTER   I 

THE    GENESIS    OF    A    WORLD 

SO  far  as  thought  may  peer  into  the  past,  the  epic  catastrophic 
of  our  solar  system  began  with  a  great  catastrophe. 
Two  suns   met.     What  had  been,  ceased ;   what  was 
to  be,  arose.     Fatal    to  both  progenitors,   the    event 
dated  a  stupendous  cosmic  birth. 

It  is  more  than  likely  that  one  or  both  of  the  col- 
liding masses  were  dark  bodies,  dead  suns,  such  as 
now  circle  unseen  in  space  amid  the  bright  ones 
we  call  the  stars.  Probable  this  is,  for  the  same 
reason  that  the  men  who  have  been  far  outnumber 
the  men  who  are.  It  is  not  to  be  supposed  that  the 
two  rovers  actually  struck,  the  chances  being  against 
so  head-on  an  encounter ;  but  the  effect  was  as  dis- 
astrous. Tides  raised  in  each  by  the  approach  tore 
both  to  fragments,  the  ruptured  visitant  passing  on 
and  leaving  a  dismembered  body  behind  in  lieu  of 
what  had  been  the  other.  That  the  stranger  con- 
tinued on  its  way  is  shown  by  the  present  moment  of 
momentum  of  our  system.  For  it  is  very  small,  and 
the  fact  can  be  proved  to  mean  that  after  the  encoun- 
ter its  matter  still  lay  massed  for  the  most  part  in  a 
3 


4  MARS   AS   THE   ABODE   OF   LIFE 

single  centre.1  Thus,  what  had  been  a  sun  was  left 
alone,  with  its  wreckage  strewn  about  it.  Masses 
large  and  small  made  up  its  outlying  fragments,  scat- 
tered through  space  in  its  vicinity,  while  a  shattered 
nucleus  did  it  for  core.  So  much  of  its  history  we 
learn  from  the  tiniest  of  its  constituents  now:  the 
meteorites.  To  meteorites  thus  attaches  a  peculiar 
importance;  for  they  are  Rosetta  stones  for  the  de- 
cipherment of  what  went  before. 

Meteorites.  From   time  unreckoned,  rocks   have  fallen  out  of 

the  sky  upon  the  Earth.  Most  of  them  are  of  stone, 
but  some  are  nearly  pure  iron,  mixed  with  a  small 
amount  of  nickel.  They  are  called  meteorites. 
Twenty-six  known  elements  have  been  found  to  occur 
in  them,  and  not  one  element  that  is  new.  They 
thus  betray  a  constitution  cognate  to  the  Earth's. 

In  size  these  visitants  vary  from  the  grain-like 
bodies  known  as  shooting-stars  up  to  ponderous 
masses  weighing  many  tons.  Coming  from  space, 
they  enter  our  air  at  speeds  of  from  eleven  to  forty- 
one  miles  a  second,  and  friction,  due  to  their  great 
velocities,  fuses  their  exterior,  and  eats  the  holes  with 
which  is  pitted  what  remains  of  them  when  they  strike 
the  ground. 

Meteorite  Recorded  meteoric  falls  date  from  a  far  past,  and 

were  deemed  miraculous  by  early  men.  A  stone  that 
fell  in  Phrygia  in  pristine  times  was  adored  as  Cybele, 


THE   GENESIS    OF   A  WORLD  5 

"  the  mother  of  the  gods,"  and  later,  about  204  B.C., 
was  carted  with  great  ceremony  to  Rome.  The  fa- 
mous Diana  of  the  Ephesians  was  probably  none  other 
than  a  meteoric  stone,  enshrined  and  worshipped  as 
a  goddess.  Adoration  of  such  arrivals  from  heaven 
was  not  of  local  observance  only,  but  common  to 
peoples  over  the  whole  Earth.  There  was  a  stone  so 
worshipped  at  Mecca,  and  another  in  Tatar,  Siberia, 
to  which  homage  was  paid  ;  while  even  in  our  own 
country  a  large  mass  of  iron  found  in  Wichita  County, 
Texas,  was  set  up  as  a  fetich  by  the  Indians,  who  re- 
vered it  as  a  body  not  of  the  Earth,  but  sent  to  it 
by  the  Great  Spirit. 

A  certain  poetic  justice  invests  this  worship  with  a  Meteoric 
grandeur  of  its  own  ;  for  these  things  are  probably  the 
oldest  bits  of  matter  we  may  ever  touch,  the  material 
from  which  our  whole  solar  system  was  fashioned. 
They  mark  the  farthest  point  in  its  history  to  which 
we  can  now  mount  back.  The  time  of  day  at  which 
they  commonly  fall  —  the  afternoon  rather  than  the 
morning  —  points  curiously  to  their  oneness  with 
the  rest  of  the  solar  system  ;  for  in  the  afternoon  the 
Earth  looks  backward  over  its  traversed  path,  and 
their  descent  then  proves  that  they  follow  and  over- 
take it,  and  therefore  that  their  movement  has  the 
same  sense  as  its  own.  Still  more  conclusive  of  their 
relationship  to  ourselves  is  the  speed  with  which  they 


6         MARS   AS   THE   ABODE   OF   LIFE 

arrive,  or,  to  be  precise,  the  lack  of  it.  For,  did  they 
come  from  the  depths  of  space,  were  they  ronins  of  the 
sky  owing  attraction's  allegiance  to  no  one  lordly  sun, 
they  would  have  velocities  exceeding  forty-five  miles  a 
second,  and  these  should  often  show,  not  an  instance 
of  which  has  ever  been  remarked.2 

Just  as,  chemically  and  gravitationally,  they  stand 
confessed  our  kith  and  kin,  so,  physically,  they  betray 
the  character  of  their  origin  ;  for  they  bear  in  them 
occluded  gases,  which  could  have  come  there  only 
under  great  pressure,  such  as  would  exist  in  the  inte- 
rior of  a  giant  sun.  Thus  they  proclaim  themselves 
clearly  fragments  of  some  greater  body.  To  the  some- 
time dismemberment  of  this  orb,  from  which  disinte- 
gration our  sun  and  planets  were  formed,  the  little 
solitary  bits  of  rock  thus  mutely  witness. 
Analogy  of  Of  the  cataclysm  that  thus  occurred  far  down  the 

cataclysm  to     otherwise  unrecorded  vista  of  time,  we  have  an  ana- 
new  stars 

(Novae).  logue  in  the  Novae  that  now  and  then  blaze  forth  in 
the  sky  to-day,  startling  us  from  out  the  depths  of 
space.  These  new  stars,  that  suddenly  appear,  grow 
in  brightness,  and  then  slowly  fade  to  nebulosity, 
speak  by  such  action  of  a  like  catastrophe  by  which 
they  were  born  again.  Not  otherwise  was  our  own 

The  meteor-    birth  heralded  in  heaven. 

ites  gravitate 

together,  Strewn  thus  about  the  scene  of  the  encounter,  the 

heat"31'          pieces  of  the  disrupted  sun  would  begin  to  gravitate 


THE   GENESIS   OF   A  WORLD 


together.  The  several  subsidiary  swarms  of  these 
fragments  were  of  different  sizes,  but  of  much  the 
same  substance,  because  of  the  general  similarity  of 
their  origin. 
Cooled  by 
contact  with 
the  cold  of 
space,  so  soon 
as  the  meteor- 
ites started  to 
fall  together, 
they  gener- 
ated heat, 
warming  one 
another,  just 
as  the  rubbing 
of  two  sticks 
strikes  fire. 
The  amount 
of  heat  pro- 
duced depended  upon  the  number  of  particles  con- 
cerned, or,  in  other  words,  upon  the  mass  of  the  body 
the  particles  were  busied  to  form. 

Approximately  we  can  compute  what  this  heat  would  Amount  of 
be.  If  the  body  be  supposed  homogeneous,  and  to  J^J^!^ 
contract  under  its  own  gravity  from  an  original  ex-  of  the  body, 
tended  condition  to  an  eventually  compressed  state, 


THE  MOREHOUSE  COMET  AS  PHOTOGRAPHED  AT  THE 

LOWELL  OBSERVATORY,  1908 

By  E.  C.  Slipher. 


8         MARS   AS   THE   ABODE   OF   LIFE 

the  work  done,  converted  into  heat,  would  be  propor- 
tionate to  the  square  of  the  mass  divided  by  the  radius 
attained.  The  same  would  be  the  case  if  the  body 
were  heterogeneous  and  composed  of  concentric  spher- 
ical shells,  only  that  the  numerical  amount  would  be 
greater  according  to  the  distribution  of  the  mass. 
However  the  body  were  constituted,  its  caloric  would 
be  spread  through  the  mass,  and  the  resulting  heat  on 
each  unit  of  it  would  therefore  be  as  its  mass  divided 
by  its  radius.  The  internal  temperature  of  the  par- 
ticular planet  would  therefore  depend  upon  the 
amount  of  material  that  collected  together.  Thus 
each  body  was  subjected  to  a  different  heat  as  well  as 
to  a  differing  pressure,  according  to  its  mass  from  the 
moment  it  began  to  form  ;  and  to  its  mass  alone,  for 
that  determined  the  radius  to  which  it  finally  stood 
compressed.8 

Substances  Now,  all  substances  behave  differently  according  to 

heal  and         t^le  temperature  and    the   pressure  under  which  they 

pressure.         exist,  both  as  to  physical  state  and  in  their  display  of 

chemical  action.      Diverse  results  ensue  from  diverse 

conditions.     The  same  element  melts  or  remains  solid, 

combines  with  another  eagerly  to  form  a  third  utterly 

unlike  both,  or  coldly  stands  aloof  from  all  association, 

solely  as  the  temperature  or  the  pressure  constrains  it 

to  that  end.      Each,  too,  is  a  law  unto  itself,  and  acts 

unlike  its  neighbor  as  these  compelling  causes  change. 


THE   GENESIS   OF   A  WORLD  9 

To  them,  therefore,  diversity  is  due ;  and  they  in  their 
turn  are  conditioned  by  the  mass. 

Mass,  then,  is  the  fundamental  factor  in  the  whole  Mass  the 
evolutionary  process,  the  determining  departure-point,  !? 
fixing  what    the    subsequent    development    shall    be. 
Though  the  bodies  were  in  essence  the  same  at  the 
start,  their    initial    quantity  would    change  their  very 
quality  as   time  went  on.       What   started   like   would 
become  different ;   for  the   gathering    together  of  the 
particles  into  a  single  body  was   the  preface   to  that 
body's  planetary  career. 

Not  until  the  internal  heat  began  to  abate  did  what 
we  call  evolution  set  in.  Up  to  then  the  growing 
temperature  induced  a  devolution  or  separating  into 
simplicity  of  what  had  been  complex.  The  time  taken 
by  each  planet  to  reach  its  maximum  bodily  heat 
differed  as  between  one  and  another.  The  larger  the 
body,  the  slower  it  attained  the  greatest  temperature  of 
which  it  was  capable,  both  by  reason  directly  of  its 
mass,  and  indirectly  of  the  pressure  to  which  that  mass 
gave  rise. 

At  its  heat-acme  the  picture  each  planet  presented  Cooling, 
was    all    its    own.     Some   may  have    been    white-hot, 
some  certainly  were  red-hot,  some  were  merely  darkly 
warm;  for  one  differed  from  another  in  self-endowment 
of  warmth  or  light,  each  with  a  glory  of  its  own. 

Radiation  had,  of  course,  been  going  on  from  the 


io       MARS   AS   THE   ABODE   OF   LIFE 


time  the  impact  of  the  particles  began.     At  first  the 
Jieat   gained    by    contraction    surpassed    that  radiated 

away,  but  at  last  a 
time  came  when  the 
depletion  exceeded  the 
generation  of  heat,  and 
the  planet  began  to 
cool.  By  parting  with 
its  caloric  into  space, 
its  surface  fell  in  tem- 
perature. Unlike  in 
amount  of  acquisi- 
tion, the  bodies  were 
no  less  unlike  in  the 
manner  of  their  loss. 
Each  acted  according 
to  its  kind.  Those 
that  originally  had  lit- 
tle, lost  that  little  fast ; 
for  volume  is  a  matter 
of  three  dimensions, 
surface  of  but  two, 
and  as  through  their  surfaces  their  volumes  cooled, 
the  smaller  got  rid  of  their  heat  with  relatively 
greater  speed.  Just  as  if  two  stones  be  put 
into  the  fire  and  then  taken  out,  the  smaller  will 
turn  cold  while  the  larger  is  yet  warm.  With  the 


METEORITE  FROM  CANON  DIABLO,  ARIZONA 

Pitted  by  fusion  in  traversing  the  earth's 
atmosphere. 


THE   GENESIS    OF   A  WORLD 


ii 


planets,  contrast  in  performance  was  accentuated  from 
the  fact  that  the  big  ones  were  intrinsically  hotter  at 
the  start.  Thus,  for  two  reasons,  the  large  lingered 
in  the  race :  they  had  more  to  lose,  and  they  lost  it 
more  reluctantly. 

In  consequence  the  life-history  of  a  planet  was  long  Life-history 
or    short   in   proportion  to  its  size.      If  little,  it  ran 
through  its  gamut  of  change  fast,  and  that  gamut  was 
itself  brief;    if  large,  it  tarried  in  its  several  stages, 
and  those  stages  were  themselves  drawn  out.      But,  in 
addition   to  this,  the   larger  knew  states  the   smaller 
in  their  heating  had  never  reached.     Diversified  age, 
both  in  length  of  years  and  in  breadth  of  experience, 
was    thus    the    first 
result  of  size. 

Six  stages  may 
conveniently  be  dis- 
tinguished in  the 
progress  of  a  planet 
from  sun  to  cinder, 
all  of  which  will  be 
traversed  by  the 
body,  if  it  be  suffi- 
ciently big.  If  it  be 
of  asteroidal  size,  it 

virtually  knows  none  of  them,  remaining  meteoric  from 
first  to  last.  The  six  periods  may  be  designated  :  — 


Planetologic 
eras. 


METEORITE  FROM  CA^ON  DIABLO,  ARIZONA 
Surface   polished.       Showing   method   of 
crystallization. 


12         MARS   AS   THE   ABODE   OF   LIFE 


Present 
aspects  of  the 
planets  our 
guide. 


I.    The  Sun  Stage.     Hot  enough  to  emit  light, 
ii.    The  Molten  Stage.     Hot,  but  lightless. 
in.    The    Solidifying    Stage.       Solid    surface    formed. 
Ocean  basins  determined.     Age  of  Metamor- 
phic  rocks. 
iv.    The    Terraqueous    Stage.      Age    of  sedimentary 

rocks. 

v.    The  Terrestrial  Stage.     Oceans  have  disappeared, 
vi.    The  Dead  Stage.     Air  has  departed. 

Though  we  cannot  in  our  own  ephemeral  life  watch 
any   planet  pass  through   these  several  phases  of  its 
career,  we  can  get  a  view  of  the 
process   by   studying   the   present 
conditions  of  the  various  planets 
and  piecing  together  the  informa- 
tion we  thus  obtain.     It  is,  in  the 
CLOUD  EFFECT  ON         end>  as   conclusive    as    in   botany 
JUPITER  would   be    the  study   of  a    wood 

As  observed  at  the  Lowell 

observatory    in    1907,    by  carefully  noting  the  condition 

indicating  that   Jupiter          c      \         *     j'    *j       1  '        ^L    ' 

isinthesecondpLeto-     of  the    '"dividual    trees    in    their 
logic  stage.  various     growths     from     seedling 

to  patriarch.  Thus,  at  the  present  moment,  in  Stage 
II  are  found  Neptune,  Uranus,  Saturn,  and  Jupiter  ; 
in  Stage  IV,  the  Earth;  in  Stage  V,  Mars;  and  in 
Stage  VI,  the  Moon  and  the  larger  satellites  of  the 
other  planets. 


THE   GENESIS    OF   A  WORLD  13 

Each  planet's  internal  heat  was  its  initial  motive- 
power,  and  cooling  the  mode  by  which  this  energy 
worked,  first,  to  the  fashioning  of  its  surface,  and  then 
to  all  evolution  upon  it.  While  still  in  the  molten 
state  the  mass  was  a  seething  chaos  but  little  differen- 
tiated from  any  other  equal  agglomeration  of  matter. 
Yet  even  here  the  several  substances  had  begun  to 
segregate,  the  heavier  falling  to  the  bottom,  the  lighter 
rising  to  the  top. 

With  Stage  III  we  enter  the  part  of  a  planet's  Geologic 
career  with  which,  on  our  Earth,  geology  is  concerned.  P*ane°olo 
Though  specifically  the  story  only  of  our  Earth,  that 
science  has  analogues  elsewhere,  and  to  be  best  under- 
stood needs  to  be  generically  considered.  Local  as 
many  Earth-happenings  are,  with  increasing  light  from 
the  heavens  it  is  becoming  clear  that  the  main  events 
are  of  cosmic  occasioning,  and  that  astronomic  cause 
presides  over  their  manifestations.  Initial  instance  of 
planetary  action  occurs  at  the  first  stage  of  the  Earth's 
history  to  which  geology  mounts  back — that  in  which 
a  crust  began  to  form  over  the  molten  mass.  The  liq- 
uid metal  in  a  furnace  upon  which  the  solidifying  slag 
has  begun  to  float  gives  us  an  idea  of  this  early  state 
of  things.  Our  metamorphic  rocks  were  in  action 
akin  to  the  furnace  slag,  rising  to  the  surface  because 
of  their  lightness.  Proof  of  this  lies  in  their  present 
density,  which  is  only  about  one-half  of  the  average 


i4        MARS   AS   THE   ABODE   OF   LIFE 

density  of  the  Earth,  2.7  times  that  of  water  instead  of 
5.5.  Their  constitution  furnishes  further  evidence 
that  such  they  were.  The  gneiss,  mica,  and  horn- 
blende of  which  they  are  composed  show  by  their 
crystalline  form  that  they  cooled  from  a  once  molten 
state,  and  their  foliation  indicates  that  they  were  crum- 
pled and  recrystallized  in  the  process. 

In  Stage  III  the  body  first  acquires  a  physiognomy 
of  its  own.  Up  to  then  it  is  a  chaotic  mass  as  unstable 
and  shifting  as  clouds  in  the  sky  ;  but  at  the  advent  of 
surface  solidification  its  features  take  form  —  a  form 
they  are  in  fundamentals  ever  afterward  to  keep.  Its 
face  is  then  modelled  once  for  all ;  and  its  face  is  the 
expression  of  its  character.  Our  knowledge  of  this 
stage  and  of  the  two  subsequent  stages  IV  and  V  is 
derived  from  study  of  three  planets  of  our  system,  the 
Earth,  the  Moon,  and  Mars.  The  others  contribute 
nothing  to  our  information  of  these  mid-phases,  either 
because,  like  Mercury  and  Venus,  they  are  too  ad- 
vanced, or  because,  like  the  major  planets,  Jupiter,. 
Saturn,  Uranus,  and  Neptune,  they  are  not  advanced 
enough. 

Landscape  Landscape  is  simply  the  sculpturing  due  the  fash- 

of cooling  ioning  cause  of  planet  physiognomy.  As  the  sub- 
stances composing  the  mass  cool,  some  of  them  expand  ; 
but  most  of  them  contract,  and  in  consequence  of  this 
the  crust  finds  itself  too  large  for  what  it  encloses. 


THE   GENESIS   OF   A  WORLD 


To  fit  the  shrunken  kernel  it  must  needs  crumple 
into  folds.  These  folds  are  what  we  know  as  moun- 
tain ranges  —  long,  low  swells  while  the  crust  is  yet 
thin,  abrupt  and  broken  fractures  when  it  has  become 
thick.  The  valleys  between  mark  the  down-folds 
of  the  squeeze. 
Wrinkles  are 
thus  as  inevitable 
a  consequence  of 
planetary  aging 
as  of  man's,  only 
that  while  they 
are  thought  a 
disfigurement  in 
him,  they  are  re- 
garded as  beauti- 
ful in  a  world. 

Such  crinkling 
of  its  cuticle  is 
most  pronounced 

where  the  heat  to 

AN  APPLE,  SHRUNK  TO  SHOW  THE  EFFECT  OF 

be  got  rid  of  is  CONTRACTION 

greatest,  and  the  surface  to  radiate  it  is  relatively 
least.  Both  conditions  are  fulfilled  the  more  com- 
pletely the  bigger  the  body.  The  larger  the  planet, 
therefore,  the  more  mountainous  its  surface  will  be 
when  it  reaches  the  crumpling  stage  of  its  career. 


Mountains  in 
proportion  to 
mass. 


16        MARS   AS   THE   ABODE   OF   LIFE 

volcanic  jn  \\fce  manner  is  volcanic  action  relatively  increased, 

phenomena. 

and  volcanoes  arise,  violent  and  widespread,  in  pro- 
portion ;  since  these  are  vents  by  which  the  molten 
matter  under  pressure  within  finds  exit  abroad.  This 
is  shown  in  their  positioning.  They  occur  where  the 
crust  is  most  permeable,  and  so  are  found  along  the 
edges  of  continents,  as  these  are  weakened  by  dipping 
down  into  the  sea. 

Relative  Three  bodies  exist  near  us  in  space  where  the  work- 

Earth  "MO™  'inS  °^  ^s  inevitable  action  stands  displayed,  and  its 
and  Mars.  comparative  effects  may  thus  be  studied:  the  Earth, 
Mars,  and  the  Moon.  With  the  accidented  character 
of  the  Earth's  surface  we  are  all  familiar.  Its  moun- 
tains, its  volcanoes,  and  its  hills  go  to  make  up  its 
loveliest  and  its  grandest  features.  Its  mass  fashioned 
them,  and  fashioned  them  as  they  are  because  its  mass 
was  large.  This  mass  is  nine  times  that  of  Mars,  and 
eighty-one  times  that  of  the  Moon.  Being  greater 
than  that  of  the  Moon  or  Mars,  our  globe  should 
have  crumpled  more,  and  those  other  two  bodies 
should  have  smoother  contours  than  the  Earth  shows. 
The  general  order  of  their  roughness  should  be 
Earth,  Mars,  Moon. 

NO  mountains  Now,  when  we  come  to  scan  Mars  with  nicety,  we 
are  gradually  made  aware  of  a  curious  condition  of  its 
surface.  It  proves  singularly  devoid  of  irregularity. 
The  more  minutely  it  is  viewed,  the  more  its  level- 


THE   GENESIS   OF   A  WORLD  17 

ness  grows  apparent.  Finally,  calculation  shows  that 
heights,  even  of  very  moderate  elevation,  should  be 
visible  if  such  existed,  and  none  show.  Thus  we  are  con- 
fronted by  the  fact  that  there  are  no  mountains  on  Mars. 

Second  only  in*  interest  to  the  fact  itself  is  the  slant 
method  by  which  that  fact  has  been  found  out.  To  mumination- 
appreciate  the  problem,  we  may  recall  the  appearance 
of  a  road  lighted  by  electric  arc-lights  placed  at  such 
considerable  distances  apart  that  the  illumination  falls 
aslant.  All  of  us  who,  on  dark  nights  in  the  country, 
have  trudged  along  such  pikes,  have  started  at  the 
mammoth  sharp-cut  shadows  of  its  ruts,  so  that  we 
have  lifted  our  feet  to  surmount  what  threatened  to 
stub  our  toes,  only  to  find  the  obstacles  not  there. 
To  such  delusion  were  we  led  by  the  monstrous 
length  of  the  shadows  thrown  with  unexpected  vivid- 
ness across  our  path. 

Now,  the  fact  of  such  projection,  —  as  Cowper  puts  important  to 
it  of  his  legs  under  the  rays  of  a  rising  or  a  setting 
sun,  "spindling  into  longitude  immense,"  —  bother- 
ing as  it  is  to  the  midnight  pedestrian  on  arc-lit  roads, 
proves  to  the  astronomer  of  inestimable  use.  For 
without  its  aid  he  had  forever  remained  incapable  of 
gaging  the  inequalities  of  the  terrene  of  the  heavenly 
bodies  to  any  fine  precision. 

When  an  object  stands  on  the  sunrise,  or  the  sun- 
set, edge  of  a   planet,  the  slant  illumination  it   then 


astronomers. 


i8        MARS   AS   THE   ABODE   OF   LIFE 

receives  throws  its  shadows  to  a  great  distance  from 
its  foot.  A  tapering  finger  searching  the  plains  as 
the  sun  changes  position,  it  may  be  a  hundredfold  the 
height  of  the  object  casting  it.  The  effect  is  well  seen 
in  photographs  of  the  moon. 

Deprived  of  this  natural  kind  of  magnification,  the 
astronomer  would  be  forced  to  measure  the  object 
itself  for  just  what  it  was,  as  it  showed  in  profile  on 
the  limb,  the  fully  illuminated  rim  of  the  planet  where 
the  sight-line  of  the  observer  grazes  horizontally  the 
surface,  and  shows  heights  for  just  what  they  are. 
With  shadows  he  has  a  vernier  to  his  hand.  For  the 
derived  may  be  any  number  of  times  longer  than  the 
original. 

On  the  same  principle,  by  noting  the  distance  off 
the  general  sun-lightened  edge  at  which  some  fortunate 
peak  first  catches  the  rays  of  the  rising  sun,  or  holds 
latest  his  setting  beams,  its  loftiness  may  be  found.4 

The  principle  has  been  employed  to  determine  the 
heights  of  the  mountains  in  the  Moon.  By  the  help 
of  trigonometry  the  shadows  and  the  star-like  tips  of 
peaks,  standing  isolate  beyond  the  general  edge  of 
light,  have  been  made  to  tell  their  tale  of  elevation. 
In  consequence,  we  know  the  heights  of  crater  walls 
there,  to  within  a  few  hundred  feet,  as  accurately  almost 
as  we  know  them  on  Earth  by  our  aneroids. 

Applied  to 

Mars.  The  same  procedure  applied  to  Mars  results  in  a 


THE   GENESIS   OF   A  WORLD  19 

negative  outcome.  While  the  sunrise  or  sunset  edge 
of  the  Moon  is  palpably  notched,  even  to  the  naked 
eye,  as  any  one  may  see  who  scans  it  carefully  a 


PHASE  VIEW  OF  THE  MOON,  SHOWING  THE  EFFECT  OF  A  MOUNTAINOUS 
SURFACE  ON  THE  TERMINATOR  (THE  DIVIDING  LINE  BETWEEN  THE 
ILLUMINATED  AND  THE  OBSCURED  PART  OF  THE  FACE) 

few  days  before  or  after  the  half,  the  similar  edge  of 
Mars  is  wonderfully  smooth  and  even.  One  may 
gaze,  armed  with  the  most  powerful  glass,  night  after 
night,  and  never  detect  the  least  irregularity  in  its 


20       MARS   AS   THE   ABODE   OF   LIFE 

elliptic  outline.  Commonly,  at  most,  he  will  notice 
slight  flattenings  here  and  there  where  a  dark  area 
happens  at  the  moment  to  be  passing  over  the  boun- 
dary of  sunlight  and  shade.  So 
rare  is  it  to  perceive  any  other 
indentation  or  excrescence  upon 
the  smooth  rim  of  its  disk  where 
the  light  fades  away,  that  to  do 
so  is  something  of  an  astronomic 

event.     The   very    rarity    of  the 
PHASE    VIEW    OF     MARS, 

MAY,    1907,     SHOWING   phenomenon  —  there     has    been 

A   SMOOTH  TERMINATOR    ,  ,  i        r    i 

(THE  CURVED   LINE   AT    but   °ne   g°°d   °ne  at  each   °f  the 

THE  LEFT),  WHICH  IN-    jast    three    oppositions  —  proves 

DICATES  THAT  THERE  ARE 

NO  MOUNTAINS  ON  THE    the  projections  not  to  be  due  to 
PLANET  what  causes  them  on  the  Moon, 

an  accidented  surface.  In  short,  they  cannot  indicate 
mountains,  for  a  mountain  is  a  permanence,  which  under 
similar  conditions  should  either  always  or  never  show. 
Now,  for  many  nights  in  succession,  indeed  for  weeks 
together,  Mars  presents  us  his  disk  under  substantially 
the  same  conditions  night  after  night;  so  that  if  the 
obstacle  that  caught  the  light  were  part  and  parcel  of 
the  surface,  however  it  might  tower  above  that  sur- 
face's customary  level,  it  should  be  seen  as  regularly 
as  the  planet's  rotation  brought  it  round.  The  fact 
that  it  fails  of  such  continuity  of  expression  is  proof 
conclusive  that  it  is  of  no  such  origin. 


THE   GENESIS   OF   A  WORLD 


21 


VIEW  OP*  THE  EARTH,  SHOWING  THE  PROPORTION  OF  LAND  AND  SEA 


Sporadicity,  then,  far  from  raising  the  slightest  pre-  Not  indicative 
sumption  in  favor  of  mountains,  or  indicating  their 
uncommonness,  is  absolutely  fatal  to  the  observed 
phenomenon  being  a  mountain  at  all.  Now,  as  none 
of  these  projections  seen  on  Mars  are  of  permanent 
appearance,  we  perceive  that  there  are  no  mountains 
on  Mars.  Such  impermanence  testifies  not  only  neg- 
atively but  positively  to  their  character.  For,  from 
the  fact  that  when  detected  two  nights  running  they 
prove  to  have  changed  their  place  in  the  interval,  we 


22       MARS   AS   THE   ABODE   OF   LIFE 


have  witness  that  they  are  unattached.  Thus  they 
come  from  something  floating  in  the  planet's  air ;  to 
wit,  clouds,  and,  furthermore,  from 
their  color,  clouds  of  dust. 

From  the  evidence  as  to  scale 
afforded  by  the  Moon,  we  can 
tell  what  height  we  ought  to  be 
able  to  detect  in  this  manner  on 

DUST  STORM  ON  MARS,  Mars.      We  find  it  by  calculation 
FROM    A    DRAWING, 

MAY  28,  1903  to  be  two  to  three  thousand  feet. 

Nothing,  therefore,  higher  than  this  modest  elevation 
exists  there,  which  leaves  us  for  contemplation  a  sur- 
face singularly  flat,  according  to  the  idea  with  which  our 
Earth  has  furnished  us.  A  Martian  landscape  would 


From  "  Old  and  New  Astronomy,"  by  R.  A.  Proctor,  Longmans,  Green  &  Co. 

Two  VIEWS  OF  THE  EARTH,  180°  APART,  SHOWING  THE  POLAR  CAPS  AND 
GENERAL  FEATURES  AS  SEEN  FROM  SPACE 

seem  to  us  remarkably  peaceful  and  tame,  —  scenery 
chiefly  noticeable  for  the  lack  of  everything  that  with 
us  goes  to  make  it  up. 

Contemplating  now  the  Moon  in  the  light  of  what 


THE   GENESIS   OF   A  WORLD  23 

we  have  thus  learned,  the  first  thought  that  strikes  us 
is  the  glaring  exception  seemingly  made  by  it  to  the 
theoretic  order  of  smoothness,  Earth,  Mars,  Moon, 
above  laid  down.  The  lunar  surface  is  conspicuously 
rough,  pitted  with  what  are  evidently  volcanic  cones 
of  enormous  girth  and  of  great  height,  and  seamed  by 
ridges  more  than  the  equal  of  the  Earth's  in  elevation. 


Two  VIEWS  OF  MARS,  ABOUT  180°  APART,  SHOWING  THE  POLAR  CAPS  AND 
GENERAL  FEATURES  FOR  COMPARISON  WITH  THE  EARTH  (AS  ABOVE) 

Many  lunar  craters  have  ramparts  17,000  feet  high, 
and  some  exceed  in  diameter  100  miles;  while  the 
Leibnitz  range  of  mountains,  seen  in  profile  on  the 
lunar  limb,  rises  nearly  30,000  feet  into  space. 

On   the   principle   that  the   internal   heat  to   cause  internal 

.         .  heat  of  the 

contraction  was  as  the  body  s  mass,  —  and  no  physical 
deduction  is  sounder,  —  this  state  of  things  on  the 
surface  of  our  satellite  is  unaccountable.  The  Moon 
should  have  a  surface  like  a  frozen  sea,  and  it  shows 
one  that  surpasses  the  Earth's  in  shagginess.  To  per- 
ceive this  more  definitely  we  will  make  that  not  unin- 
teresting thing,  an  evaluation  of  the  heat  evolved  by 


24        MARS   AS   THE   ABODE   OF   LIFE 

both  the  Moon  and  the  Earth,  supposing  their  origin 
the  same.  We  will  express  it  in  terms,  if  not  in  fig- 
ures, that  are  comprehensible.  The  result  is  startling. 
Unaccountable  at  a  first  view,  the  event  proves  actually 
impossible  when  we  subject  the  heat  evolved  by  a  like 
genesis  to  numerical  computation.  If  the  Earth  con- 
tracted homogeneously  from  an  infinite  expansion  to  its 
present  state,  and  none  of  its  heat  were  lost  meanwhile 
by  radiation,  calculation  shows  that  the  energy  evolved 
would  be  sufficient  to  raise  the  temperature  of  its  en- 
tire mass  to  146,000°  F.,  if  that  mass  were  composed 
of  iron,  which  represents  about  its  present  density  and 
is  probably  not  far  from  the  fact.  If  it  were  com- 
posed of  other  material,  the  temperature  of  that 
material  would  be  different,  according  to  its  capacity 
for  heat.  Thus  quartz  has  a  capacity  nearly  twice 
that  of  iron  (sp.  ht.  0.20)  and  water  one  of  five  times 
as  much  (sp.  ht.  i.oo).  The  temperatures  would  be 
reduced  in  proportion. 

If,  instead  of  supposing  the  body  homogeneous,  we 
consider  it  heterogeneous,  as  indeed  it  is,  and  treat  it  by 
the  simplest  law  consistent  with  physical  principles  and 
an  approach  to  fact,  to  wit,  that  the  density  increases 
from  surface  to  centre  and  that  it  resists  compression 
in  proportion  as  it  stands  compressed, —  the  formula 
assumed  by  Laplace, —  we  get  an  even  greater  amount 
of  heat  generated. 


THE   GENESIS    OF   A  WORLD  25 

We  do  not  know  the  law  of  parting  with  this  heat, 
though  the  greater  portion  of  it  was  certainly  radiated 
away  in  the  process.  But  we  may  make  some  approx- 
imation, at  least  as  between  the  several  planets  con- 
cerned, by  assuming  the  heat  near  the  surface  to  have 
been,  at  its  maximum,  what  a  body  contracting  from 
the  density  of  its  constituents,  the  meteorites,  to  its  own 
eventual  density  would  generate.  We  do  this  because 
the  heat  thus  begotten  proves  in  the  case  of  the  Earth 
to  have  been  more  than  sufficient  for  all  the  volcanic 
and  erogenic  phenomena  displayed.  Now,  as  it  is 
common  physical  knowledge  that  a  small  body  cools 
quicker  than  a  large  one,  we  shall  not  err  on  the  side  of 
making  Mars'  internal  heat  too  small  if  we  apply  the 
same  principle  to  it.  When  we  so  evaluate  the  heat 
for  the  Earth  and  Moon,5  we  get  results  as  follows:  — 
23,000°  F.  and  80°  F. 

Here,  then,  we  are  landed  in  a  quandary.  If  the 
Moon  was  generated  on  its  own  account,  as  the  Earth 
and  Mars  were,  the  internal  heat  it  was  able  to  amass 
was  never  anything  like  the  amount  sufficient  to  pro- 
vide for  the  features  which  its  surface  shows.  It  could 
not  even  have  kept  itself  from  freezing  amid  the 
terrible  cold  of  space.  Now,  it  will  be  noticed  that 
we  said  "  if  its  genesis  was  like  our  own " ;  that  is, 
that  it  came  into  being  by  itself  alone.  In  this  saving 
"if"  will  be  found  the  explanation  of  the  dilemma. 


26       MARS   AS   THE   ABODE   OF   LIFE 

Darwinian  Some  years  ago  Sir  George  Darwin  showed  analyti- 

iuna7origin      ca^Y  that  t^le  acti°n  of  the  tides  in  the  Earth- Moon 

system,  when  traced  backward,  lands  us  at  a  time  when 


Confirmed   by 
lunar  surface. 


From  a  photograph  taken  at  the  Lowell  Observatory. 
A  PART  OF  THE  MOON'S  FACE,  SHOWING  ANCIENT  SEA-BOTTOM 

the  Moon  might  have  formed  a  part  of  the  Earth's 
mass,  the  two  rotating  together  as  a  single  pear-shaped 
body  in  about  five  hours.  His  analysis  pointed  to 
what  might  have  been.  Now  the  pregnant  point  in 
our  present  heat  inquiry  is  that  the  face  of  our  satellite 
indicates  that  the  might-have-been  actually  was. 

The  erupted  state  of  the  Moon's  surface  speaks  of 
such  a  genesis.     For  in  that  event  the  internal  heat 


THE    GENESIS    OF   A   WORLD  27 

which  the  Moon  carried  away  with  it  must  have  been 
that  of  the  parent  body — the  amount  the  Earth-Moon 
had  been  able  to  amass.  Thus  the  Moon  was  en- 
dowed from  the  start  of  its  separate  existence  with  an 
amount  of  heat  the  falling  together  of  its  own  mass 
could  never  have  generated.  Thus  its  great  craters 
and  huge  volcanic  cones  stand  explained.  It  did  not 
originate  as  a  separate  body,  but  had  its  birth  in  a  rib 
of  Earth. 

Far  from  disproving  the  law,  the  seeming  lunar  ex- 
ception, therefore,  really  upholds  it. 

We  may  now  go  on  to  apply  the  principle  to  no  Probable 
less  interesting  a  determination  —  the  case  of  Mars.6  jC°^7h«t 
If,  taking  into  account  the  radiation  which  has  cease-  of  earth  and 
lessly  gone  on  from  the  time  when  first  the  matter 
started  to  collect,  we  allow  10,000°  F.  for  the  effective 
internal  heat  of  the  Earth,  we  shall  be  making  it  a 
liberal  allowance.  Now,  computation  shows  that  an 
internal  heat  of  10,000°  F.  for  the  Earth  would  cor- 
respond to  about  2000°  F.  for  Mars.  But  the  melt- 
ing-point of  iron  is  2200°  F.,  so  that  iron  would  not 
have  fused,  and  we  should  have  in  consequence  virtu- 
ally no  volcanic  action.  Furthermore,  there  could 
have  been  but  little  crinkling  of  the  crust.  For,  first, 
the  direct  pressure  was  less,  and  then  the  heat,  its  indirect 
effect,  was  correspondingly  small ;  so  that  Mars  can- 
not have  contracted  much,  and  so  must  largely  have 


28        MARS    AS   THE    ABODE    OF    LIFE 

escaped  crumpling.  What  the  contraction  was  may  be 
inferred  from  comparison  of  its  density  with  that  of 
meteorites.  The  mean  density  of  meteorites  which 
are  mostly  stone  with  some  iron  is  3.5,  that  of  Mars 
4.,  and  that  of  the  Earth  5. 5,  water  being  unity.  The 
planet  should  show,  therefore,  a  remarkably  smooth  and 
level  surface  ;  and  this  is  precisely  what  the  telescope 
reveals. 

The  crust,  to  the  folding  of  which  a  planet's  physi- 
ognomy is  due,  was  forming  during  all  the  time  the 
planet  took  to  cool  on  its  surface  from  the  temperature 
of  the  fusion-point  of  gneiss  to  the  boiling-point  of 
water,  or  from  about  2000°  F.  down  to  212°  F.  In 
some  places  it  gathered  thicker  than  in  others ;  and 
inasmuch  as  it  floated,  stood  up  higher,  to  which  height 
crumpling  contributed.  Up  to  the  time  when  its 
liquefaction-point  was  reached,  water  existed  only  in  the 
form  of  steam,  but  on  the  fall  of  the  temperature  to 
212°  F.  the  steam  fell  with  it,  condensing  into  water. 
Into  the  troughs  already  there  the  water,  as  soon  as  it 
formed,  proceeded  to  run.  Thus  the  oceans  came  inta 
being. 

We  may  apply  this  to  the  Earth  and  consider  an 
important  consequent  detail.  The  fashioning  cause  of 
the  depressions  that  gave  rise  to  the  distribution  of 
what  we  know  as  continents  and  seas  is  of  great  in- 
terest, for  it  seems  to  have  been  determined  in  a 


THE   GENESIS   OF   A  WORLD  29 

general  way  by  cosmic  considerations.  If  we  scan  a 
map  of  the  globe,  we  shall  mark  a  significant  fact : 
that  in  all  the  continents  a  certain  apexing  to  the  south 
is  discernible.  Witness  North  and  South  America, 


VIEW  OF  MARS,  SHOWING  THE  PROPORTION  OF  DARK  AND  LIGHT  AREAS 

The  dark  areas  are  probably  old  sea-bottoms,  and  the  light  ones,  desert  land. 
Mars  is  here  given  of  its  true  relative  size  as  regards  the  Earth  on  page  21  — 
so  that  the  actual  surface  of  its  former  seas  as  well  as  their  relative  proportion 
to  the  land  areas  may  be  compared  with  those  of  the  Earth. 


Greenland,  Africa,  and  India.  Blunt-based  to  the 
north,  they  all  terminate  in  a  tip  southward.  Australia 
is  the  only  one  of  the  great  continental  masses  that 
fails  to  show  the  peculiarity  at  first  glance.  But  a 


30       MARS   AS   THE   ABODE   OF   LIFE 

bathymetric  chart  reveals  the  fact  that  the  platform  on 
which  it  stands  does  indeed  do  so,  Tasmania  being 
really  a  part  of  it  and  making  the  detached  tip. 

True  Martian  Nor  does  the  Earth  alone  present  us  with  such 
curious  conformations,  for  Mars  has  a  word  to  say  on 
the  subject.  On  casting  one's  eye  over  a  map  of  that 
planet,  one  is  struck  by  the  triangular  projections  of 
the  dark  areas  into  the  northern  hemisphere.  The 
Syrtis  Major  is  the  most  conspicuous  instance ;  but 
the  Margaritifer  Sinus,  the  Sabaeus  Sinus,  and  the 
Trivium  Charontis  exhibit  a  similar  propensity. 
Now,  when  we  reflect  that  the  dark  regions  take  the 
place  of  seas  on  Mars,  this  apexing  of  them  to  the 
north  stands  as  the  negative  aspect  of  the  positive 
picture  presented  by  the  Earth.  Reverse  the  relative 
ratio  of  depressions  to  plateaux  in  order  to  get  the 
seas  and  continents  in  their  earthly  proportions,  with 
the  oceans  preponderant,  as  on  Earth,  instead  of,  as  on 
Mars,  in  abeyance,  and  the  two  distributions  are  seen 
to  typify  the  same  action. 

Their  relative       The  amount  of  surface  the  oceans  covered  on  any 

size  on  dif-  •       i  i  •  c      t_ 

ferent  lanets  Partlcu'ar  planet  was  again  a  consequence  or  the 
particular  planet's  size.  If  the  material  forming  the 
planetary  bodies  was  of  the  same  general  character 
throughout  the  fields  they  severally  swept  clear,  which, 
to  a  certain  extent,  is  probable,  and  the  more  so  as 
the  planets  stand  neighborly  near,  the  amount  of 


THE   GENESIS   OF   A  WORLD  31 

water  each  possessed  would  be  as  its  mass,  and  when 
it  collected  into  seas,  these,  if  equally  deep,  would 
cover  more  of  the  surface  in  the  larger  planet,  since  it 


VIEW  OF   THE    MOON   AT    THE    FULL,    SHOWING   THE    PROPORTION    OF   DARK 

(SO-CALLED  "SEAS")  AND  LIGHT  AREAS 

Only  the  darkest  patches  are  thought  to  be  sea-bottoms. 
Moon  of  true  relative  size  to  Earth  (page  21)  and  Mars  (page  29). 

has  less  cuticle  for  its  contents.  We  have  seen,  how- 
ever, that  this  cuticle  would  be  more  crinkled  and  of 
greater  accentuation  in  the  larger  body,  owing  to  a 
greater  contraction  in  the  kernel  within ;  the  folding 
we  may  perhaps  take  as  being  roughly  proportionate 
to  the  radius  of  the  globe.  The  larger  body  would, 


32        MARS    AS   THE   ABODE    OF   LIFE 

therefore,  begin  life  with  larger  oceans,  even  if  it  were 
born  with  but  its  share  of  water ;  but,  as  a  fact,  it 
would  have  more  than  its  share  because  of  being 
better  able  to  hold  on  to  its  gaseous  elements,  and 
thus  retain  more  of  what  was  to  condense  to  water 
when  the  time  arrived. 

Now  the  three  bodies,  the  Earth,  Mars,  and  the 
Moon,  have,  or  had,  in  all  probability,  judging  from 
their  present  look,  oceans  in  this  order  of  size,  the 
Earth  having  the  most  in  amount,  Mars  the  next,  and 
the  Moon  the  least. 

In  the  case  of  the  Moon  the  matter  is  complicated 
by  the  fact  that  when  it  left  the  Earth  it  took  probably 
not  only  a  greater  amount  of  light  constituents  than  a 
solitary  genesis  would  have  permitted,  but  even  a 
greater  proportion  than  the  Earth  retained  since  it  was 
born  of  the  outer  and  therefore  lighter  layers  of 
the  Earth-Moon  mass.  It  thus  started  more  pro- 
fusely endowed  with  the  wherewithal  to  oceans  than 
its  size  warranted. 

Earth's  On  all  three  planets  their  primeval  topography  has 

oceanic  basms  provecj  persistent.     On  both  the  Moon  and  Mars  the 

unchanged.         * 

dark  areas  are  apparently  the  lowest  portions  of  the 
surface,  while  their  character  points  to  their  having 
held  seas  once  upon  a  time.  With  Mars  it  is 
their  present  occupancy,  though  by  something  other 
than  water,  that  tells  the  tale ;  with  the  Moon  the  fact 


THE   GENESIS   OF   A  WORLD  33 

that  rays  and  rills  run  athwart  them  discloses  it,  be- 
speaking their  age. 

Turning  to  the  Earth,  according  to  the  best  evidence 
we  possess,  the  great  ocean  basins  have  remained  un- 
changed in  place  from  the  period  when  they  were  laid 
down.  Not  that  the  areas  marked  out  as  land  and 
water  at  any  epoch  have  not  greatly  altered  since  the 
beginning  of  geologic  time;  but  the  abyssal  depths  on 
the  one  hand,  and  the  continental  platforms  on  the 
other,  have  not  substantially  varied  during  all  these 
ages.  If  we  examine  a  bathymetric  chart  of  our 
several  oceans,  giving  their  body  by  registering  their 
depth,  instead  of  a  superficial  one  which  marks  simply 
where  the  water  laps  the  land,  and  consider  the  one 
hundred-fathom  line,  the  ocean  bottoms  and  the  con- 
tinental plateaux  stand  well  differentiated  from  each 
other.  It  is  then  seen  that  each  continent  is  set  on  a 
shelf  wider  in  some  places  than  in  others,  but  at  its 
edge  falling  abruptly  to  the  marine  abysses,  which, 
though  themselves  uneven,  stand,  with  the  exception 
of  a  few  islands,  projecting  and  submarine,  at  a  gener- 
ally much  lower  level.  This  indicates  that  they  have 
always  held  such  attitude. 

But  the  character  of  these  ocean  bottoms  furnishes  Their  floor- 
the  best  testimony  that  they  have  not  changed  during  insattes 
geologic  time.     Their  flooring  is  organic  ooze  or  inor- 
ganic  clay,   globigerina,   radiolarian,   or   diatom  ooze, 


34       MARS   AS   THE   ABODE   OF   LIFE 

according  to  locality  and  depth,  and  red  clay  formed  of 
the  decomposition  of  volcanic  stuff.  In  this  ooze  and 
clay,  spherules  of  metallic  iron,  identified  as  similar  in 
substance  to  that  of  falling  stars,  are  still  recognizable 
in  perceptible  amount,  and  as  they  must  accumulate 
with  exceeding  slowness,  their  patent  presence  asserts 
the  absence  there  of  sedimentary  silt  from  any  shore. 
These  abysses,  then,  have  always  been  abysses  from 
the  start.  That  astronomy  should  tell  us  this  is 
strikingly  suggestive,  while  of  peculiar  planetologic  in- 
terest is  it  that  meteors  again  should  be  our  inform- 
ants of  the  fact. 


CHAPTER    II 

THE    EVOLUTION    OF    LIFE 

V 

UPON  the  fall  of  the  temperature  to  the  condensing  The  origin 
point  of  water,  occurred  another  event  in  the  °ife°r8a 
evolution  of  our  planet,  the  Earth,  and  one  of  great 
import  to  us  :    life  arose.      For  with  the  formation  of 
water,  protoplasm  (the  physical  basis  of  all  plants  and 
animals)  first  became  possible,  what  may  be  called  the 


MODEL  OF  A  BRONTOSAURUS,  A  FIRST  POSSESSOR  OF  THE  EARTH'S  LAND,  IN 
THE  AMERICAN  MUSEUM  OF  NATURAL  HISTORY* 

The  fossil  skeleton  is  15  ft.  and  2  in.  high  and  66  ft.  and  8  in.  long. 

life  molecule  then  coming  into  existence.  By  it, 
starting  in  a  simple,  lowly  way,  and  growing  in 
complexity  with  time,  all  vegetable  and  animal  forms 

*  This  illustration  and  those  succeeding  it  to  page  41  were  kindly  furnished  the 
author  for  the  purpose,  by  Professor  Osborn. 

35 


36        MARS   AS   THE   ABODE   OF   LIFE 


have    since    been    gradually    built  up.     In  itself  the 
organic    molecule    is    only  a  more   intricate   chemical 
combination  of  the  same  elements  of  which  the  inor- 
•^••••••BBnHHmEBIieMB  ~"  '    ganic     substances 

1    which  preceded  it 
are  composed.     It 
'    is  thus  carrying  on 
I    the      building-up 
]    process  begun  by 
the  inorganic  be- 
\    fore  it.      Between 
j    the    organic    and 
I  \          the  inorganic,  in- 
A        creasing      knowl- 
A      edge,  by  pushing 
back    to    greater 
and  greater    sim- 
plicity the    forms 
of  life  discovered, 
has      tended      to 
break    down    the 
barrier    man    had 
j    assumed  to  exist. 
There  is  now  no 


1M.AN-,     I.H.K    IN   THE   COA,    MKASU^ 

From  a  fossil  specimen  in  the  American  Museum  of       QOUDt    that    plants 


Natural   History,  found  in  Illinois,  here  shown 

two-thirds  its  size. 


r     , 

grew  out  of  chem- 


THE   EVOLUTION   OF   LIFE  37 

ical  affinity  than  to  doubt  that  stones  did.  Spon- 
taneous generation  is  as  certain  as  spontaneous  varia- 
tion, of  which  it  is,  in  fact,  only  an  expression. 

But  it  is  not  spontaneous  generation  in  the  popular 
sense.  By  that  term  many  persons  think  of  flies 
suddenly  born  of  decaying  meat,  and  this  they  know 
has  been  shown  impossible.  But  this  is  simply  be- 
cause flies  are  far  too  advanced  a  product  to  be  thus 
suddenly  evolved.  For  them  to  be  so  produced 
would  as  directly  controvert  all  we  know  of  evolution 
as  that,  given  the  proper  conditions,  the  lowest  rudi- 
ments of  life  would  not  arise.  That  even  the  latter 
may  nowhere  be  evolved  on  earth  at  the  present  time 
does  not  invalidate  such  origin  for  it  when  the  con- 
ditions were  other  than  they  are  to-day. 

From  all  we  have  learned  of  its  constitution  on  the  Life  an  in- 
one  hand,  or  of  its  distribution  on  the  other,  we  know  ^Llta  "* 
life  to  be  as  inevitable  a  phase  of  planetary  evolution  evolution. 
as  is  quartz   or   feldspar  or    nitrogenous    soil.      Each 
and  all  of  them  are  only  manifestations  of  chemical 
affinity  resultant    on    condition,   and    considering    the 
oneness    of  the  stuff,   it  is  the    conditions  alone  we 
have  to  investigate  if  we  would  learn  what  is  to  come. 

Virtually  only  six  so-called  elements  go  to  make  up 
the  molecule  of  life.  It  is  the  number  of  its  constituent 
atoms,  and  the  intricacy  of  their  binding  together,  that 
give  it  the  instability  to  produce  the  vital  actions. 


38        MARS   AS   THE   ABODE   OF   LIFE 


Carbon,  hydrogen,  oxygen,  nitrogen,  phosphorus,  and 
sulphur  are  practically  all  that  are  required.  If  a 
planet  be  capable  of  furnishing  these  under  suitable 
^_ __M_B—1^________  temperature  con- 
ditions, it  seems 
as  inevitable  that 
life  will  ensue  as 
that  the  two  ele- 
ments sodium  and 
chlorine  will  unite 
to  form  common 
salt  when  the  heat 
and  the  pressure 
are  right.  Now, 
on  its  face,  it  is 
suggestive  of  the 
u  ni  versality  of  life 
that  the  elements 
that  go  to  form  it 
are  of  all  elements 

the    most    wide- 
i 
spread.    Oxygen, 

PLANT  LIFE  OF  THE  UPPER  DEVONIAN  the     chief     factor 

From  a  fossil  specimen  in  the  American  Museum       in    all    Organisms, 
of  Natural  History,  found  in  New  Brunswick.  makes    by   weight 

one-half    the     substance     of     the      earth's     surface ; 
silicon,  a  large   constituent    of  shells,  comes  next  in 


THE   EVOLUTION   OF   LIFE  39 

amount ;  and  the  others  follow  in  the  constitution  of 
life  about  in  the  order  of  their  natural  abundance. 
For  proof  of  the  continuity  of  the  processes  of  both 
structure  and  change  in  the  inorganic  and  organic  alike, 
nothing  at  once  more  conclusive  and  more  interesting 
can  be  recommended  than  the  books  of  the  great 
Haeckel,  couched  in  language  every  educated  person 
can  understand. 

Of  all  the  conditions  preparatory  to  life,  the  presence  Water 
of  water,  composed  of  oxygen  and  hydrogen,  is  at  once  ^ntl 
the  most  essential  and  the  most  world-wide.  For  if 
water  be  present,  the  presence  of  other  necessary  ele- 
ments is  probably  assured  because  of  its  relative  light- 
ness as  a  gas.  Furthermore,  if  water  exist,  that  fact 
goes  bail  for  the  necessary  temperature,  the  gamut  of 
life  being  coextensive  with  the  existence  of  water  as 
such.  It  is  so  consequentially,  life  being  impossible 
without  water.  Whatever  the  planet,  this  is  of  neces- 
sity true.  But  the  absolute  degrees  of  temperature 
within  which  life  can  exist  vary  according  to  the  mass 
of  the  body,  another  of  the  ways  in  which  mere  size 
tells.  On  the  earth  212°  F.  (100°  C.)  limits  the  range 
at  the  top,  and  32°  F.  (o°  C.)  at  the  bottom  in  the  case  of 
fresh  water,  27°  F.  ( —  3°  C.)  in  the  case  of  salt.  On  a 
smaller  planet  both  limits  would  be  lowered,  the  top 
one  the  most.  On  Mars  the  boiling-point  would  prob- 
ably be  about  1 10°  F,  (43°  C.).7  Secondly,  from  the 


40        MARS    AS   THE   ABODE   OF   LIFE 

general  initial  oneness  of  their  constituents,  a  planet  that 
still  possesses  water  will  probably  retain  the  other  sub- 
stances that  are  essential  to  life :  gases,  for  the  reason 


A  TRILOHITE,  ONE  OF  THE  EARLIEST  FORMS  OF  ANIMAL  LIFE  PRESERVED 

From  the  fossil  specimen  in  Niagara  shale,  in  the  American  Museum  of  Natural 
History,  here  shown  two-fifths  natural  size. 

that  water-vapor  is  next  to  hydrogen,  and  helium  the 
lightest  of  them  all ;  and  solids  because  their  weight 
would  still  more  conduce  to  keep  them  there.  Water, 
indeed,  acts  as  solution  to  the  whole  problem. 

Water  plays  a  protagonist  part   in   the    origination 
and   the   development  of  protoplasm  by  constituting 


THE   EVOLUTION   OF   LIFE 


at  least  nine-tenths  of  its  substance.  But,  to  begin 
with,  it  actually  furnished  the  stage-setting  for  the 
drama  of  life  by  providing  a  medium  in  which  it 
could  evolve  and 
function.  This  all- 
important  use  of 
water  by  living 

J  o 

organisms  is  shown 
both  by  the  pres- 
ent state  of  all  ani- 
mals and  plants  and 
by  what  science  is 
discovering  of  their 
past  history. 
There  never  was 
a  time,  and  there 
apparently  never 
will  be  a  time,  when 
plasm  can  do  with- 
out that  indispen- 
sable ingredient  of 
life.  At  first,  in 
the  lowest  unicellu- 
lar plants  and  animals,  it  forms  the  whole  environment, 
completely  enveloping  the  organism.  Thus  the  simplest 
cells  are  found  in  the  sea,  in  ponds,  and  even  in  hot- 
spring  geysers  nearly  at  the  boiling-point.  In  fact, 


FOSSIL  FOOTPRINTS  OF  AMPHIBIA 

From  a  slab  reproduced  in  Professor  Edward 
Hitchcock's  "  Report  on  the  Sandstone  of  the 
Connecticut  Valley." 


42        MARS   AS   THE   ABODE   OF   LIFE 


Seas  the 
earliest  home 
of  mundane 
life. 


far  from  this  last  habitat  being  peculiar,  it  is  in  such 
warm  baths  that  plasm  undoubtedly  took  its  rise. 
Protophyte  and  protozoa  lived  in  a  sea  that  to  us 
would  have  been  fatally  hot. 

Here  is  the  reason  for  the  contemporaneous  ap- 
pearance of  oceans  and  of  life  :  the  one  was  the  neces- 
sary home  of  the  other.  That  it  was  so  in  fact 
geology  states.  The  geologic  record  proves  that  life 
originated  in  the  oceans,  and  lived  there  for  long  eons 
before  it  so  much  as  crawled  out  upon  the  land.  Seas 
were  the  nurseries  of  mundane  life.  Whether  life 

might  have  gen- 
erated on  land 
we  do  not  know  ; 
on  earth  it  cer- 
tainly did  not, 
possibly  because 
seas  were  intrin- 
sically the  better 
habitat  in  place 
and  in  time  for 
the  uniformity 
of  the  conditions 
they  offered  ;  possibly  because  they  were  all  the  home 
there  was.  For  the  land  was  a  sorry  spectacle  in  those 
days.  Granite  fringed  by  mud-flats  pictures  but  an  in- 
hospitable sight.  The  seas  were  much  as  they  are  now, 


SPECIMENS  OF  DEEP-SEA  FISH 

These  specimens  were  obtained  by  the  Challenger  Expe- 
dition from  a  depth  of  about  500  fathoms  (3000  feet). 
They  illustrate  life  formerly  thought  impossible. 


THE   EVOLUTION   OF   LIFE  43 

only  warmer.  Their  equable  temperature  for  wide  locali- 
ties and  their  slow  accommodation  to  climatic  change 
rendered  them  places  of  easy  livelihood  to  simple  organ- 
isms. In  addition  to  which,  food,  inorganic  at  first,  was 
floated  past  the  'baby  plants  or  animals,  and  as  con- 
stantly renewed.  To  its  seas  and  oceans  our  planet, 
then,  is  actually,  if  not  necessarily,  indebted  for  the 
life  which  now  teems  everywhere  upon  its  surface. 

Life,  once  started,  continued  the  course  of  advance- 
ment thus  aquatically  begun  just  as  itself  was  the 
continuance  of  the  inorganic  development  which  had 
gone  before.  And  the  deus  ex  machina  was  the  same 

—  a  gradual  lowering   of  temperature.     Cooling  was 
what  occasioned  increasingly  high  forms  of  life,  and  in 
two  ways  this  was  simultaneously  brought  about  —  by 
preparation  of  habitat  and  by  prompting  of  the  organ- 
ism to  appropriate  it. 

The  record  written  in  the  rocks  of  our  own  earth 
permits  us  to  trace  the  history  of  the  spread  of  life. 
With  the  gathering  of  the  waters  into  their  place 
began  a  new  stage  in  the  world's  physiographic  career 

—  the   stage    of  sedimentary  formations.     Until    the 
seas  were,  no  strata   could    be   laid  down ;    but  with 
their  advent  both  motive  force  and  suitable  sites  were 
present,    and,    in  consequence,  what  the  welkin-born 
torrents  tore  down  of  the  naked  earth  was  deposited 
over  the  edges  of  the  continents,  now  here,  now  there, 


44       MARS   AS   THE   ABODE   OF   LIFE 

according  as  upheaval  or  subsidence  slightly  changed 
the  continental  altitude  toward  the  sea-level.  One 
bed  after  another  was  thus  made,  until  they  were  sev- 
eral thousand  feet  thick  in  places,  each  being  tucked  into 
its  long  repose  by  later  coverlets  superposed  upon  it. 
Entombed  in  these  strata  are  the  skeletons  of  all 
those  animals  that  a  not  too  flimsy  structure  permitted 
to  survive  the  casualties  of  flood  and  commotion  or 
the  long  disintegration  of  time.  The  softer  ones  have 
necessarily  vanished,  leaving  as  a  rule  no  trace.  The 
rocks  are  thus  vast  graveyards  of  life  that  once  inhab- 
ited the  earth.  They  give  us  the  only  direct  record 
of  the  past,  and  a  record  which  from  the  necessities  of 
the  case  is  perforce  imperfect.  Especially  are  the 
earlier  chapters  effaced  for  the  gelatinous  character  of 
primeval  protoplasm  and  the  forms  it  first  built  up. 
Thus  the  earliest  preserved  remains  of  life  are  already 
somewhat  advanced  types,  Crustacea  in  the  shape  of 
trilobites  being  the  most  primordial  specimens  that 
have  come  down  to  us  in  unquestionable  state.  From 
this  lowly  start  the  line  can  be  followed  upward,  un- 
folding through  the  strata,  the  marvellous  thing  being 
not  the  paucity,  but  the  fulness,  of  the  record  thus 
written  by  the  animals  themselves.  For  animals  and 
plants,  too  perishable  to  endure,  have  left  their  stamp 
behind,  and  even  footprints  of  past  reptiles  confront 
us,  legible  still  on  the  hardened  sands  of  time,  as  if 


THE   EVOLUTION   OF   LIFE  45 

made  yesterday  in  the  spots  they  traversed  hundreds 
of  centuries  ago. 

According  to  their  age,  the  rocks  are  designated  by  Uniformity 
geologists  as  primary,  secondary,  or  tertiary  formations, 
representing  paleozoic,  mesozoic,    and   oenozoic  eras, 
meaning  the  old,  the  middle,  and  the  new  lifetimes,  so 
called  from  the  remains  embedded  in  them. 

For  our  purpose,  the  most  remarkable  characteristic 
of  the  primary  rocks  consists  in  the  world-wide  uni- 
formity of  their  contemporary  life  as  exhibited  in  these 
fossils  of  the  far  past.  In  the  earliest  beds  existent 
species  prove  to  have  been  coevally  widespread.  In 
the  Cambrian,  the  lowest  of  the  primary  strata  exhibit- 
ing unmistakable  organic  remains,  we  find  identical 
species  of  seaweeds  and  trilobites  appearing,  regardless 
of  latitude,  in  France  and  Siberia;  and  indifferently  on 
both  sides  of  the  equator,  in  the  Argentine  Republic, 
as  in  Europe  and  North  America.  In  the  beds  above 
these,  the  Silurian,  it  is  the  same  story.  Some  of  the 
genera  and  even  some  identical  species  have  been 
found  alike  in  Europe  and  North  America  and  in  Tas- 
mania, Australia,  and  New  Zealand.  Evidence  of  a 
like  latitudinarianism  is  forthcoming  in  the  Devonian 
deposits  that  followed  them  and  in  the  early  stages  of 
the  succeeding  Carboniferous. 

The  fauna  so  distributed  was  a  warmth-loving  one, 
an  attribute  betrayed  by  the  fact  that  their  nearest 


46       MARS   AS   THE    ABODE   OF   LIFE 

relatives  now  extant  live  wholly  within  the  tropics, 
huddled  as  it  were  about  the  equator.  Coral  reefs, 
now  not  found  outside  of  the  warm  equatorial  seas  in 
a  temperature  not  less  than  68°  F.,  were  reared  then  in 
spots  now  covered  with  perpetual  ice,  within  eight 
degrees  of  the  pole.  A  species  of  polyp  coral,  Litho- 
strontion  by  name,  has  been  found  as  a  fossil  between 
Point  Barrow  and  Kotzebue  Sound,  and  others  in 
Grinnell  Land  in  latitude  81°  45'  north. 

At  first  the  fauna  was  wholly  marine,  but  gradually 
the  land  grew  less  impossible.  Wings  of  insects  have 
been  found  in  the  Lower  Silurian,  and  in  the  Upper, 
insects  themselves,  scorpions  both  aquatic,  apparently, 
and  terrene.  Vestiges  of  plants  in  the  Devonian  fore- 
shadowed the  superb  plant  life  of  the  Carboniferous, 
carboniferous  The  flora  of  the  coal  measures  corroborates  the  tes- 
timony of  the  animals  of  that  day  to  the  climatic 
warmth  which  then  existed.  Gigantic  ferns,  fifty  feet 
high  ;  others,  more  lowly,  thirty  feet  in  spread  ;  marsh- 
loving  calamites,  horsetails,  and  club-mosses,  dignified 
to  the  dimensions  of  trees,  spread  their  incipient  leaves 
from  well-nigh  woodless  stems,  and  grew,  flourished, 
and  decayed  with  almost  Jack-and-the-beanstalk  rapid- 
ity between  33°  and  70°  of  latitude.  Only  a  warm, 
humid  foothold  and  lambent  air  could  have  given  them 
such  luxuriance  and  impressed  them  with  such  speed. 

In  the  vast  marshes  which  constituted  so    large  a 


THE   EVOLUTION   OF   LIFE  47 

portion  of  the  continents  this  vegetation  was  singularly 
same.  Not  pretty,  but  profuse  ;  dense,  but  not  varied, 
cryptogams  composed  its  greater  part,  attesting  by  the 
habit  of  the  ferns  of  to-day  to  the  shady  half-light  in 
which  they  must*  have  lived.  Grotesque  rather  than 
beautiful,  no  flowers  touched  with  color  the  sombre 
stems.  No  birds  made  the  air  about  them  half  sentient 
with  song.  Only  shade-affecting  insects,  May-flies  of 
mammoth  wing,  flitted  through  the  gloom  of  those  old 
forests,  accentuating  a  heavy  stillness  they  were  power- 
less to  dispel. 

The  twilight  their  character  thus  reveals  is  shown 
by  the  details  of  their  structure  to  have  been  continu- 
ous. No  seasons  diversified  the  work  of  wood-making, 
as  the  uniform  stems  of  the  few  gymnosperms  then 
present  attest.  No  annual  rings  of  growth  encircle 
them,  witnessing  to  intermediate  times  of  rest.  They 
minded  not  extraneous  things,  but  grew  right  on ;  not 
to  delight  the  world,  but  to  make  coal  measures  their 
industrious  end,  to  which  in  their  own  blind  way  they 
excellently  conformed.  Blind  in  their  habit  they  may 
be  said  to  have  been,  for  they  were  flowerless  and 
much  restricted  of  leaf. 

Two  attributes  of  the  climate  this  state  of  things 
attests.  First,  it  was  warm  everywhere  with  a  warmth 
probably  surpassing  that  of  the  tropics  of  to-day  ;  and, 
second,  the  light  was  tempered  to  a  half-light  known 


48        MARS    AS   THE   ABODE   OF   LIFE 

now  only  under  heavy  clouds.  And  both  these  con- 
ditions were  virtually  general  in  locality  and  continuous 
in  time.  For  such  vegetation  as  existed  the  climate 
was  ideal.  No  enforced  hiemal  torpor  brought  on  by 
stalking  delegates  of  frost  compelled  the  workers  con- 
stantly to  stop.  It  is  their  less  fortunate  descendants 
only  that  are  limited  by  nature's  imposings  to  labor 
but  six  months  a  year. 

Light  less  and  Thus  the  records  of  the  paleozoic  rocks  bespeak  two 
tiTnToT  seemingly  incongruous  things  —  both  less  light  and 
more  heat  than  is  the  Earth's  lot  nowadays.  Many 
hypotheses  have  been  invoked  to  account  for  this 
warm  dawn  of  the  early  geologic  ages.  Some  of  them 
are  locally  geologic,  some  broadly  astronomic,  advanced 
by  geologists.  But  of  the  two  kinds  all  alike  fail. 

Thus,  merely  a  different  distribution  of  land  and 
sea  will  not  explain  it,  because  it  was  general,  not  local; 
and,  secondly,  because  this  leaves  untouched  the  prob- 
lem of  less  light.  Equally  impotent  is  a  change  of 
position  in  the  axis  of  the  Earth ;  for  were  the  axis  so 
far  changed  as  to  point  directly  toward  the  sun,  this 
would  not  do  away  with  the  seasons,  but  would  accen- 
tuate them.  Nor  will  an  altered  eccentricity  in  the 
Earth's  orbit,  which  has  also  been  suggested,  prove 
more  effective. 

Not  less  impossible  is  the  suggestion  due  to  M. 
Blondet,  and  to  which  De  Lapparent  has  lent  the 


THE   EVOLUTION   OF   LIFE  49 

weighty  indorsement  of  his  name,  that  the  sun  was 
then  so  large  as  to  be  able  to  look  down  on  both  poles 
of  the  Earth  at  once,  and  so  to  give  our  globe  equal 
day  and  night  everywhere  and,  as  he  supposes,  a  sub- 
stantially even  temperature  in  consequence  throughout. 
Here  the  beauty  of  that  to  many  people  deterrently 
austere  and  awe-enshrouded  subject,  mathematics, 
comes  in.  For  it  enables  us  to  do  that  most  impor- 
tant thing  for  any  line  of  investigation  —  to  subject  it 
not  simply  to  qualitative,  but  to  quantitative,  reasoning. 
When  we  thus  calculate  what  this  paleozoic  sun  must 
have  been  and  what  its  effects,  we  are  brought  up  on 
both  counts  against  impossibilities. 
•  The  first  impossibility  relates  to  the  sun  itself.  For 
it  to  do  as  desired  it  must  have  filled  all  the  space 
inside  the  orbit  of  Mercury.  For  a  sun  of  such  stu- 
pendous size  there  is  no  place  in  modern  cosmogonies. 
On  the  other  hand,  it  would  have  been  of  incredible 
tenuity,  only  one-fifth  as  dense  as  hydrogen  gas. 
Nor  is  this  all.  It  must  have  been  thus  uncondensed 
at  a  time  when  the  Earth  had  already  solidified.  The 
conception  evolutionarily  is  quite  incredible.8 

Matters  are  not  bettered  for  the  theory  if,  passing  Effect  on  the 
by   the   results  consequent  on  the    Sun,  we  calculate 
those  ensuing  to  the  Earth. 

We  perceive,  in  the  first  place,  that  the  exposure  to 
the  Sun's  rays  in  the  arctic  regions  would  have  been 


50        MARS    AS    THE   ABODE   OF    LIFE 

by  no  means  uniform,  but  would  have  varied  greatly 
with  the  time  of  year.  At  latitude  82°  N.,  for  instance, 
the  exposure  would  have  been  virtually  nothing  at 
midwinter;  25  per  cent  of  what  it  would  be  now  at 
the  equator,  at  the  vernal  equinox,  and  1.24  per  cent 
of  that,  at  the  summer  solstice.  So  that  the  play  of 
the  seasons  would  have  been  much  as  now. 

Secondly,  we  find  that  at  the  arctic  circle  the  solar 
heat  in  midwinter  would  equal  that  at  present  in  lati- 
tude 60°  N.,  and  even  at  the  equinox  82°  N.  in  those 
times  would  be  no  more  heated  than  is  now  46°  N.  in 
midwinter.  A  Quebec  winter  six  months  long  does 
not  quite  supply  an  adequate  temperature  for  the 
bringing  up  of  a  polyp  coral  family  within  ten  degrees 
of  the  pole.9 

So  that,  when  subjected  to  mathematical  treatment, 
the  supposed  paleozoic  sun  turns  out  to  be  quite  im- 
potent to  the  work  demanded  of  it.  The  theory  fails 
as  regards  the  Earth  as  much  as  it  does  with  reference 
to  the  Sun. 

Earth  itself  Planetology,  however,  can  offer  us  a  clew  to  this  be- 

°r  clouded  hothouse  state  of  things.     The  Earth's  own 

paleozoic  neat. 

heat,  not  directly  on  the  crust,  but  directly  on  the 
water,  and  thence  through  its  atmosphere,  might  well 
be  responsible  for  paleozoic  conditions.  For  consider 
the  warmth  we  know  must  have  existed  while  the  re- 
cently precipitated  seas  still  were  hot.  Their  temper- 


THE   EVOLUTION   OF   LIFE  51 

ature  would  furnish  an  agreeably  heated  habitat  for 
organisms  such  as  even  the  tropics  fail  to  supply  to- 
day, and  one  which  from  its  genesis  would  be  much  the 
same  from  the  equator  to  the  poles.  Simultaneously, 
a  vast  steaming  must  have  gone  up  from  the  still 
warm  waters,  resulting  in  a  welkin  of  great  density. 
This  would  act  in  two  ways  to  explain  the  phenomena. 
First,  the  welkin  would  keep  the  Earth/ s  own  heat 
in;  and,  secondly,  it  would  keep  the  Sun's  heat  and 
light  out.  We  should  have  a  sort  of  perpetual  trop- 
ical summer  in  a  twilight  of  cloud;  a  climate  superior 
to  seasons  because  screened  from  direct  dependence 
on  the  elevation  of  the  sun.  This  is  perfectly  in  ac- 
cord with  the  half-light  the  vegetation  vouches  for, 
while  the  luxuriance  of  that  vegetation  testifies  to  the 
warmth  and  even  suggests  a  further,  though  not  the 
chief,  reason  for  it  in  the  great  amount  of  carbonic 
dioxide  its  existence  establishes  as  then  present  in  the 
air.10  For  carbonic  dioxide  is  a  great  bar  to  the  pas- 
sage of  heat.  So  is  water-vapor.  It  was  dank  and 
dark  in  those  old  carbonic  forests  because  so  seeth- 
ingly  steamy  overhead. 

That  the  oceans  should  have  retained  their  heat  so 
long  is  not  surprising  when  we  reflect  upon  the  great 
capacity  that  water  has  for  heat.  Its  specific  heat, 
which  means  the  relative  amount  needed  to  raise  it  one 
degree  in  temperature,  is  five  times  that  of  stone,  and 


52        MARS    AS   THE   ABODE   OF    LIFE 

ten  times  that  of  iron.  So  that  it  would  have  more  to 
part  with  than  its  surroundings,  and  would  still  be 
warm  and  steamy  after  they  had  cooled. 

Earth,  not  In  paleozoic  times,  then,  it  was  the  Earth  itself,  not 

motive  force     tne   sun>  t°  which   plant  and   animal   primarily  stood 
in  evolution      beholden  for  existence.      This  gives  us  a  most  instruc- 

in  the  pale-  ... 

tive  glimpse  into  one  planetologic  process.     To  the 


ozoic  era. 


planet's  own  internal  heat  is  due  the  chief  fostering  of 
the  beginnings  of  life  upon  its  surface.  Thus  a  planet 
is  capable  of  at  least  beginning  to  develop  organisms 
without  more  than  a  modicum  of  help  from  the  central 
sun.  We  talk  of  the  sun  as  the  source  of  life  ;  and  so 
it  is  to-day  in  the  sense  of  being  its  sustainer ;  but  the 
real  source  was  the  Earth  itself,  which  also  raised  it 
through  its  babyhood. 

A  once  Something  of  the  same  history  probably  fell  to  the 

lot  of  Mars.  Several  circumstances  render  this  likely. 
If  its  initial  surface  temperature  was  in  the  neighbor- 
hood of  2000°  F.,  it  was  well  above  the  production- 
point  of  steam.  So  that  a  cloud  canopy  would  be 
possible  when  a  general  volcanic  'fervor  of  the  surface 
was  not.  Then  the  apparent  presence  in  those  early 
days  of  seas  would  furnish  the  wherewithal  of  clouds. 
Thus  Mars  would  seem  to  have  possessed  the  neces- 
sary substance  to  its  veiling,  and  the  requisite  con- 
ditions to  that  end.  If  a  planet  be  big  enough  to 
bring  forth  life,  it  may  well  provide  a  set  of  atmos- 


THE    EVOLUTION   OF   LIFE  53 

pheric  swaddling-clothes  in  which  that  life  goes  through 
its  early  days. 

Under  such  paleozoic  conditions  life  passed  the  first  Life  outgrow* 
eons  of  its  earthly  existence.  Gradually  life  outgrew 
the  need  of  such  careful  housing,  water  within  the 
organism  remaining  as  necessary  as  before.  Organic 
development  proceeded  from  amoeba  to  fish,  attaining 
no  mean  height  in  the  process.  But  at  last  a  better 
habitat  offered  itself,  and  was  speedily  appropriated. 
Weathering  of  the  land  and  constantly  changing 
chemic  processes  prepared  the  continents  for  organic 
use.  Plants,  as  we  have  seen,  at  last  found  foothold, 
and  insects  an  abode.  Then  came  the  exodus  from 
the  sea.  We  may  picture  some  adventurous  fish, 
spurred  blindly  from  within,  essaying  the  shore  in 
preference  to  the  main.  Tentatively  at  first  he  must 
have  ventured,  as  became  such  bold  endeavor.  Find- 
ing the  littoral  not  inhospitable,  the  pioneer  reported 
his  exploit  and  was  followed  by  others  whom  mutation 
had  specially  endowed.  This  impulse  toward  the  new, 
from  the  promptings  of  altered  character,  which  we  call 
spontaneous  variation,  is  the  motive  principle  of  life. 
It  probably  derives  from  the  instability  of  the  plasmic 
molecule,  forever  rearranging  its  constitution  afresh 
and  finding  itself  thus  adapted  to  novel  relations. 
Thus  arose  the  amphibia  in  the  Carboniferous  era,  vis- 
itors only  to  the  solid  ground.  From  them  came  the 


54       MARS   AS   THE   ABODE   OF   LIFE 

reptiles,  their  descendants,  in  the  Permian,  who,  from 
the  temporary  sojourners  their  fathers  were,  devel- 
oped into  permanent  denizens  of  the  new  abode. 
From  this  aboriginal  crawling  out  upon  terra  firma 
the  organism  progressed  until  finally  it  came  to  stand 
erect  and  call  itself  a  man. 

Changed  habitat  made  all  the  later  strides  in  intelli- 
gence possible.  The  very  sameness  that  rendered  the 
sea  so  inviting  a  habitat  to  simple  souls,  made  evolu- 
tion beyond  a  certain  point  difficult,  if  not  impossible. 
Change  might  develop  in  the  organism,  but  it  would 
find  little  encouragement  to  survive  in  its  surround- 
ings. 
Effect  of  It  was  the  variety  of  conditions  possible  on  land 

environment         i  •  •  •  j      L  •      • 

evoiu-  tnat  §ave  nse  to  varymg  environment,  and  this  in  turn 
that  conduced  to  organic  differentiation.  Life  would 
have  remained  forever  of  a  low,  cold-blooded  order  if 
it  had  been  constrained  to  continue  in  the  sea.  What 
made  the  broad  ocean  so  excellent  a  nursery  curtailed 
it  as  a  field  for  action  later  on. 

To  appreciate  how  unsuited  to  high  development 
of  organism  the  sea  was,  we  need  only  think  how  poor 
a  place  it  is  for  bringing  up  a  family.  Fishes  cast 
their  spawn  upon  the  waters,  and  leave  the  hatching 
of  the  eggs  to  chance.  If  one  in  a  million  survives 
this  unparental  treatment,  it  is  all  that  nature  expects. 
The  fish  has  done  well,  and  its  tribe  increase.  This  is 


tion. 


THE   EVOLUTION   OF   LIFE  55 

taking  but  little  thought  for  the  morrow.  The  poor 
little  egg  is  homeless  as  well  as  parentless  from  the 
start,  lacking  even  that  attenuated  appreciation  of  home 
surroundings  Gallicly  expressed  as  mal  du  pays,  since 
one  tract  of  ocean  so  dishearteningly  resembles  another. 

Very  different  is  the  care  of  their  young  exhibited 
by  the  higher  land  inhabitants,  the  mammalia.  With 
them  the  mother  begins  by  carrying  the  egg  in  the 
safest  possible  way,  as  a  part  of  herself,  until  it  has 
become  to  all  intents  and  purposes  an  animal  on  its 
own  account.  It  then  sees  the  light,  but  not  the  limit 
of  fostering  care.  She  keeps  it  by  her,  suckling  it  till 
it  is  able  to  procure  food  for  itself.  Even  then  its 
guardianship  is  not  in  the  highest  forms  foregone.  In 
man  parental  help  continues  up  to  the  point  when  the 
young  is  full  grown,  and  even  after  that,  on  through 
life,  till  the  next  generation  has  become  the  dominant 
one  of  its  day. 

To  say  the  least,  life  was  an  arduous,  adventurous 
career  amid  the  inhospitable  homelessness  of  the  sea. 
And  this  is  shown  not  only  by  the  leaving  it  at  the 
first  opportunity  by  those  who  could,  but  by  only 
degenerates  returning  to  it  again.  Only  the  poor 
relatives  of  the  mammalia  —  the  porpoises,  dugongs, 
and  whales — are  now  to  be  found  there,  having  taken 
to  it  through  stress  of  circumstances,  elbowed  off  the 
better  ground  by  their  stronger  associates. 


56       MARS   AS   THE   ABODE   OF   LIFE 

That  the  outcasts  still  exist,  however,  proves  the 
tenacity  and  adaptability  of  life.  It  goes  everywhere, 
takes  up  with  what  it  can  get,  and  turns  the  least  pro- 
pitious milieu  to  its  own  ends.  For  life  is  more  univer- 
sal than  is  our  usual  conception  of  it.  Our  limited 
personal  experience  we  take  as  measure  of  the  whole, 
and  say,  "  Thus  far  and  no  farther."  But  nature 
knows  no  such  limit  to  her  own  possibilities.  And 
we  are  gradually,  one  may  almost  say  reluctantly, 
learning  them  of  her.  Go  where  he  will  upon  the 
earth,  man  finds  life  of  some  sort  there  before  him. 
He  discovers  new  continents  or  seas  merely  to  find 
out  that  they  had  been  discovered  by  some  poor  rela- 
tives long  ago,  and  appropriated  by  them.  From 
burning  Saharas  to  polar  snows  no  spot  is  exempt 
from  colonization,  though  some  teem  with  immigrants 
more  than  others.  In  altitude  it  is  the  same  story  as 
in  latitude.  If  man  ascends,  he  meets  with  forms  of 
life  that  rise  with  greater  facility  than  he,  and  inhabit, 
too,  what  they  explore.  In  descent  it  was  until  re- 
cently thought  otherwise.  One  region  was  supposed 
free  of  such  intrusion  and  to  have  remained  as  virginly 
azoic  as  when  originally  formed — the  unstirred  abysses 
of  the  vast  oceanic  basins,  all  that  constitutes  the  great 
deep  beyond  the  immediate  vicinity  of  the  shore  and 
below  the  hundred-fathom  line.  No  life  existed,  man 
was  sure,  in  the  depths  of  the  sea. 


THE   EVOLUTION   OF   LIFE  57 

Fifty  years  ago  the  absence  of  both  flora  and  fauna  Deep-sea  life 
from  the  deep  seas  was  not  only  taken  for  granted,  but  '^JJ^ 
believed  on  the  most  conclusive  grounds  to  have  been  y^"  ago- 
proved  inevitable.     The  first  of  these  was  the  enor- 
mous pressure  to"  which  any  organisms  resident  there 
would  be  subjected.     From  the  weight  of  the  super- 
incumbent water  the   pressure  would   increase  at  the 
rate  of  one  ton   per  square   inch  for  every  thousand 
fathoms  of  descent. 

Consequently,  at  the  bottom  of  the  Atlantic,  it  would 
be  from  two  and  a  half  tons  to  three  and  three-quarters 
tons  per  square  inch,  and  in  the  greater  depths  of  the 
Pacific  from  three  and  one-half  to  nearly  five  tons. 
On  bodies  at  the  earth's  surface,  living  only  under  the 
ocean  of  air,  it  is  but  fifteen  pounds  to  the  square  inch. 
From  fifteen  pounds  to  ten  thousand  is  a  far  cry,  and 
one  it  staggers  imagination  to  understand.  It  was 
only  too  easily  argued  as  prohibitive  to  life.  Any 
organism  there,  it  was  thought,  would  simply  be 
crushed  out  of  existence. 

The  second  bar  was   the   total  extinction  of  light.  Extinction 
Below  two  hundred  fathoms   no  sunlight   could   pos-      1*lfc 
sibly  penetrate.     So   it  was   calculated  from   the   rate 
at  which  light  is  absorbed   at   lesser   depths,  and   the 
calculation    was    amply    borne    out    by    observation. 
Experiments   by  Fal   and  Sarasin   have   fully  demon- 
strated  the    unassailability  of  this   deduction.     On   a 


58       MARS   AS   THE   ABODE   OF   LIFE 

sunny  day  in  March  they  exposed  bromo-gelatin 
plates  for  ten  minutes  at  a  depth  of  two  hundred 
fathoms  without  a  trace  of  reaction.  To  those  who 
know  by  experience  how  quickly  plates  fog  in  a  dark- 
room, this  immunity  speaks  for  the  more  than  Stygian 
darkness  which  must  there  prevail. 

Now,  the  lack  of  light  is  distressing  enough  to  any 
fauna,  but  to  flora  it  is  absolutely  preclusive,  since 
light  is  the  necessary  stimulus  to  chlorophyl  reaction, 
and  thus  to  the  growth  of  the  plant.  But  if  all  plants 
be  absent,  animals,  it  was  confidently  concluded,  must 
be  absent,  too,  since  they  could  not  live  without  plants, 
being  unable  to  fashion  their  food  out  of  inorganic 
substances.  They  must  eat  plants  or  other  animals 
that  have  eaten  plants.  Therefore,  after  the  stronger 
inhabitants  of  these  abyssal  depths,  supposing  any 
there,  had  eaten  the  weaker,  they  must  themselves  die 
of  starvation. 

These  arguments  seemed  unanswerable,  to  say  noth- 
ing of  the  abyssal  cold.  For  the  temperature  falls  as 
the  thermometer  descends  until  at  a  depth  of  a  few 
hundred  fathoms  in  the  unbarriered  ocean  basins  it 
reaches  a  temperature  of  34°  F.,  whence  a  slow  falling 
further  brings  it  to  29°  F.,  or  actually  below  the  freez- 
ing-point of  fresh  water. 

Deep-sea  life.         When   it   had   thus   been   conclusively  proved  that 
no  life  could  exist  at  the  bottom   of  the  sea,  deep- 


THE   EVOLUTION   OF   LIFE 


59 


SPECIMEN  OF  A  DEEP-SEA  FISH 

This  specimen  was  obtained  by  the  Challenger  Expedi- 
tion from  a  depth  of  about  500  fathoms  (3000  ft.)  and 
illustrates  life  formerly  thought  impossible. 


sea  dredges  were  invented,  and  no  sooner  were  they 
let  down  than,  behold  !  they  came  up  teeming  with 
life.  Fish  and 
Crustacea,  mol- 
lusks  and  echi- 
noderms  —  life, 
in  short,  of  all 
the  usual  pelagic 
kinds  from  pro- 
toplasmic mole- 
cules to  marine  monsters  —  were  found  to  inhabit  the 
abysmal  depths.  What  could  not  be,  just  was. 

The  abyssal  fauna  thus  disclosed  proved  to  be  in 
comfortable  circumstances,  in  spite  of  the  supposed 
impossibility  of  its  existence  at  all.  It  had,  it  is  true, 
no  visible  means  of  subsistence,  but  it  subsisted,  never- 
theless. It  was  as  widespread  as  it  was  abundant,  en- 
joying a  distribution  unknown  on  land.  The  same 
species  were  found  off  the  coast  of  Europe  and  about 
New  Zealand,  in  the  arctic  seas  as  well  as  under  the 
tropics.  This  was  because  of  the  uniformity  of  the 
habitat.  Only  seven  degrees  of  difference  in  temper- 
ature distinguished  one  part  of  its  huge  domain  from 
another.  There  was  therefore  no  bar  to  migration ; 
indeed,  the  sameness  of  the  surroundings  must  have 
insidjously  led  the  inhabitants  on.  A  species  was  thus 
induced  to  become  world-wide,  while  on  land,  even 


60        MARS   AS   THE   ABODE   OF   LIFE 

supposing  a  pathway  to  exist,  the  journey  from  one 
hemisphere  to  the  other  involved  enduring  a  shift  of 
100°  F.  or  150°  F.  of  temperature,  made  as  it  would 
be  from  winter  in  the  one  to  summer  in  the  other. 
No  such  temporalities  as  seasons  disturb  the  abyssal 
pelagic  denizens,  nor  can  locality  have  meaning  to 
them,  even  though  they  be  associated  with  the  bot- 
tom, which  is  only  ooze  or  mud  —  ooze,  the  burial- 
ground  of  protozoa,  and  mud,  the  siftings  of  volcanic 
lava  mixed  with  meteoric  dust.  One  place  is  like 
another,  bearing  no  earmark,  and  a  fish  returning  to 
the  very  spot  of  its  nativity  would  not  know  it  again. 
Time  and  space  are  alike  annihilated  there,  and  both  to 
sense  made  limitless.  If  any  creatures  can  feel  infinity, 
it  must  be  these  abyssal  denizens  of  the  deep  sea. 
Blindness.  The  supposed  impossibilities  of  their  abode  Nature 

has  contrived  to  surmount.  The  pressure  permeates 
them,  and  their  parts  are  constructed  to  stand  the 
strain.  Yet  so  little  change  has  been  needed  to  adapt 
them  that  it  is  virtually  imperceptible  to  the  cursory 
eye.  In  another  way  Nature  has  accommodated  them 
to  the  illumination  of  their  habitat.  She  has  let  them 
get  on  without  seeing  or  she  has  provided  them  with 
lamps.  By  supplying  senses  other  than  the  eye,  and 
allowing  the  animals  to  become  blind,  Crustacea  and 
fishes  alike,  she  has  made  them  independent  of  the 
darkness.  Or  she  has  done  for  them  what  man  has 


THE   EVOLUTION   OF   LIFE  61 

accomplished  for  himself — supplied  artificial  illumina- 
tion. That  a  blind  fauna  should  exist  in  a  vast  do- 
main with  not  so  much  as  a  one-eyed  specimen  for 
king,  is  interesting  and  suggestive  of  what  Nature  can 
contrive  to  do  without,  but  that  she  should  undertake 
to  light  the  region,  and  that  by  means  of  the  creatures 
themselves,  is  yet  more  surprising. 

But  this  is  precisely  what  she  does,  and  with  some-  Phospho- 
thing  akin  to  electricity,  each  animal  carrying  with  it 
its  own  machine.  Whole  tracts  are  brilliantly  lighted 
up  by  the  inhabitants  till  they  must  resemble  London 
or  Paris  seen  by  night,  only  that  in  these  thoroughfares 
of  the  abysses  of  the  sea  the  passers-by  provide  the 
illumination,  each,  as  it  swims  about,  swinging  its  own 
lantern  as  in  old  Japan,  though  better  —  a  phospho- 
rescent arc-light,  as  one  may  say.  These  devices  are 
evident  even  when  the  fish,  no  longer  living,  reaches 
the  surface  in  the  dredge ;  much  more  brilliant  they 
must  be  in  their  native  wastes  of  abysmal  water,  where 
all  is  cold  and  dark  and  silent  round  about,  as  impres- 
sive as  a  mountain  top  at  midnight,  standing  con- 
fronted with  the  stars. 

How  thoroughly  the  living  by  artificial  light  is  now  Lesson  of  the 

c     ,      .  ,  ,  r  fishing  fishes. 

a  part  or  their  everyday  existence,  the  occupation  of 
angling  practised  as  a  means  of  livelihood  by  certain 
of  the  fish  themselves  —  fish  that  fish  and  are  known 
in  consequence  as  angler-fish  —  will  serve  to  show. 


62        MARS   AS   THE   ABODE   OF   LIFE 

On  the  surface  the  genus  given  to  this  profession  are 
furnished  with  a  long  tentacle  which,  rising  from  the 


- 

by  its  weight  till 
the  end,  which  is 

lobed  into  a  red 

m-  '  'taSr 

bunch    not    un- 

-  '  "    ^^^^^^BB^: 

suggestive    of    a 

^^^^^ 

terrmtinpr    worm. 

SPECIMEN  OF  A  DEEP-SEA  FISH                   dangles    righ(.    jn 

This  globular  specimen  is  an  angler-fish,  which  has    r                       c        .1 
kept  to  the  habit  of  angling,  but  has  changed  its  bait. 

From  the  Challenger  Expedition.                                        fisher's        HlOUth. 

Smaller  fry,  attracted  by  this  bright  bait,  dart  forward 
to  gulp  it,  and  are  themselves  snapped  up  by  the 
expectant  jaws. 

Now,  of  these  angler-fish  one  species  proves  to  in- 
habit the  abyssal  zone  ;  and  this  relative  of  the  anglers 
above,  instead  of  the  red  worm-like  bait  at  the  end  of 
its  rod,  which  would  be  useless  in. the  Stygian  darkness 
thereabout,  has  replaced  it  by  a  brilliant,  phosphores- 
cent light,  which  lures  as  certainly  to  destruction. 
Adaptation  could  offer  no  more  expressive  example 
of  the  insistence  of  life,  even  to  the  preservation  of 
the  very  type,  than  this  keeping  of  the  fishing  habit 
with  only  a  change  of  bait. 

After  such  an  ingenious  transformation,  the  substitu- 
tion of  lungs  for  gills  when  the  aquatic  animal  changed 


THE   EVOLUTION   OF   LIFE  63 

into  the  terrestrial  one,  seems  a  forthright  step  in 
comparison.  The  swim-bladder,  discarded  when  the 
descendants  of  the  upper  relatives  of  these  animals 
emerged,  leads  to  some  curious  experiences  at  the 
bottom  of  the  sea  —  ones  that  induce  new  outlooks 
on  life,  and  yet  are  the  result  of  conditions  alone.  To 
us  who  live  upon  the  solid  crust,  pulled  downward 
constantly  by  gravity,  danger  lies  in  falling  over  preci- 
pices or  down  holes.  Abyssal  fish  are  exposed  to  no 
less  a  risk,  but  of  precisely  the  opposite  character  — 
that  of  tumbling  upward.  Within  limits,  the  fish 
has  control  of  his 
swim-bladder,  but 
if  in  the  excite- 
ment of  the  chase  SPECIMEN  OF  A  DEEP-SEA  FISH 
he  gets  Carried  by  Obtained  by  the  Challenger  Expedition. 

impetuosity  farther  up  than  he  intended,  he  may  reach 
regions  where,  for  the  lessened  pressure,  he  can  no 
longer  control  its  distention,  and  is  swept  against  his 
will  higher  and  higher  till  his  organs  burst  from  the 
released  strain.  The  fish  tumbles  upward,  and  is 
killed  by  the  fall. 

As  for  the  flora,  it  simply  does  not  exist.  Never- 
theless, the  absence  of  a  local  food  supply  is  not  fatal 
to  these  denizens  of  the  deep.  It  would  seem  that 
what  descends  to  them  from  the  waters  above  is 
enough,  meagre  as  it  may  be.  They  feed  off  the 


64       MARS   AS   THE   ABODE   OF   LIFE 

crumbs  that  fall  from  the  better-spread  table  of  their 
littoral  relatives,  as  is  shown  by  their  being  the 
descendants  of  emigrants  thence.  For  most  of  them 
have  relatives  still  living  in  shallow  water,  the  oldest 
abysmal  species  not  dating  farther  back  than  Cretaceous 
times. 

Cosmk  char-  From  such  world-wide  distribution  of  life  over  the 
Earth  under  conditions  which  are  antagonistically 
unlike,  we  realize  its  essentially  cosmic  character 
experimentally,  if  we  may  so  put  it,  as  well  as 
theoretically.  Modifications  of  it  follow  any  and 
every  change  of  environment,  but  nature  strives  to 
the  last  gasp  to  bring  forth  this,  her  highest 
product. 

Each  planet  sets  a  different  stage  for  the  play  of 
spontaneous  variation.  In  no  two  is  the  scenery  the 
same,  but  this  is  not  essential  to  organic  origin  and 
growth.  Nor  are  many  of  the  environmental  circum- 
stances prohibitive,  though  at  first  they  seem  fatal  to 
our  particular  species  of  life.  Because  a  man,  if  sud- 
denly transported  to  Mars,  would  gasp  and  die,  is  as 
beside  the  point  in  any  inquiry  into  the  existence 
of  life  there  as  the  fact  that  no  woman  ever  was  the 
mother  of  a  monkey  is  irrelevant  to  a  discussion  on 
the  origin  of  man.  We  have  here  been  evolving  in 
keeping  with  the  shapings  of  a  certain  environment. 
To  suppose  that  we  could  instantly  prove  adapted 


THE   EVOLUTION   OF   LIFE  65 

to  another  quite  diverse  is  to  mistake  the  process 
upon  which  life  depends. 

Indeed,  our  most  commonplace  actions  would  there 
seem  phantasmagoric.  Personal  experience  of  Mars, 
on  the  surface  of  which  gravity  is  only  three-eighths 
the  Earth's,  would  take  on  a  character  akin  to  the 
grotesque.  Everything  there  would  become  unnatu- 
rally light :  lead  would  weigh  no  more  than  stone  with 
us,  stone  than  water,  each  substance  appearing  to  be 
transmuted  into  something  other  than  itself.  It  would 
prove  at  once  a  world  imponderable,  etherealized. 
Our  actions  would  grow  grandific.  For  with  little 
effort  we  should  accomplish  the  apparently  impossible, 
endowed  with  an  effectiveness  increased  sevenfold. 
Lastly,  everything  would  take  its  time.  Water  would 
flow  with  hesitant  and  lazy  current,  and  falling  bodies 
sink  with  graceful  moderation  to  the  ground.  After 
our  first  paranoeac  wonder,  it  would  certainly  impress 
us  as  a  world  as  slow  as  it  was  flat. 

Our  very  senses  would  seem  estranged.  Sight, 
indeed,  and  taste  would  be  the  only  ones  not  to  be 
shifted  in  their  point  of  view.  Touch,  hearing,  even 
smell,  would  all  suffer  a  space-change  and  prove  quite 
other  than  we  know  them  now.  We  should  be  any- 
thing but  at  home.  But  this  does  not  imply  that  life 
of  some  form  would  not.  For  consider  how  our 
own  world  must  seem  other  than  we  know  it  to  every 


66       MARS   AS   THE   ABODE   OF   LIFE 

animal  upon  its  face.  To  the  ant  it  stands  a  very 
different  habitat  from  what  the  elephant  conceives  it. 
The  grass-spires  which  tower  as  trees  to  the  one  are 
trodden  unnoticed  underfoot  by  the  other.  Nor  is  it 
matter  of  mere  magnification  alone.  The  former  feels 
both  strength  and  limitations  the  latter  quite  ignores. 
The  ant  scales  his  grass-stem  with  an  ease  and  assur- 
ance we  should  not  know  on  trees,  and  falls  off  to  the 
ground,  if  need  be,  completely  unscathed  from  a  rela- 
tive height  that  would  terminate  our  careers  forthwith. 

But  though  modified  in  feeling  by  size  of  habitant 
and  modified  in  fact  by  size  of  habitat,  life  would  go 
on  superior  to  such  detail  were  the  planet  only  sizable 
enough  to  furnish  it  with  its  necessities. 

So  far  as  we  have  evidence,  life  is  an  inevitable 
outcome  of  the  cooling  of  a  globe,  provided  that 
globe  be  sufficiently  large.  For  life  did  not  reach 
this  earth  from  without.  No  fanciful  meteorite  bore 
it  the  seeds  which  have  since  sprouted  and  overrun  its 
surface.  Meteorites  gave  it  life,  indeed,  but  in  the 
more  fundamental  way  in  which  all  nature's  processes 
are  done,  by  supplying  it  with  matter  only  from  which 
by  evolution  life  arose.  Of  this  we  may  be  absolutely 
certain  from  the  fact  that  while  meteors  were  falling 
upon  it  in  any  numbers,  they  were  forming  its  mass, 
the  full  heat  of  which  had  not  yet  been  evolved  by 
their  impact  and  subsequent  condensation.  The  heat 


THE   EVOLUTION   OF   LIFE  67 

that  thence  ensued  was  excessive,  many  fold  greater 
than  sufficed  to  kill  any  germs  that  might  have  come 
to  it  housed  in  the  meteorites  themselves.  Thus  the 
action  due  the  meteorites  after  they  came  must  have 
annihilated  any  organic  possibilities  they  may  have 
brought  with  them.  Those  arriving  after  the  heat 
had  waned  enough  to  make  survival  possible  found 
life  already  started,  since  protoplasm  formed  the  mo- 
ment cooling  permitted  of  it. 

The  proof  that  life  was  here  spontaneously  evolved 
appears  at  every  stage  in  its  history,  not  only  in  its 
origin,  but  at  every  step  of  its  progress  upward  where 
a  marked  departure  occurs  from  its  previous  course. 
It  and  the  environment  are  observed  to  have  changed 
together.  Two  short  parallel  columns,  the  one  show- 
ing the  changes  that  have  occurred  in  the  habitat,  the 
other  those  supervening  in  the  habitant,  will  make 
this  not  simply  clear,  but  striking.  As  effective  as 
the  well-known  deadly  parallel  of  oratorical  utterances, 
this  life-giving  one  reaches  the  same  certainty  through 
the  probabilities  disclosed. 

Occasion  of  this  vital  parallelism  occurs  at  the  very 
start.  Indeed,  we  may  go  back  of  this  and  note 
agreement  before  the  start.  For  until  the  conditions 
were  such  as  could  support  life,  no  life  appeared. 
This  is  the  first  coincidence.  Another  follows  on  its 
heels  with  the  dawn  both  of  conditions  fit  for  some 


68        MARS    AS    THE    ABODE   OF   LIFE 

existence  and  of  that  existence  itself.  The  waters 
were  its  birthplace.  No  other  portion  of  the  surface 
could  then  have  offered  it  a  home,  and  nowhere  ex- 
cept in  the  sea  is  it  then  found. 

The  simultaneity  of  each  new  birth  and  each  new 
cradle  crops  up  again  when  a  new  field  arose  by  the 
making  of  the  land.  As  soon  as  this  was  suitable, 
plants  appeared  to  take  possession  of  it,  and  from 
that  time  on  neglected  more  and  more  the  sea. 

The  fourth  parallel  is  found  in  the  significant  fact 
that  the  edible  plants  and  the  plant-eaters  made  their 
debut  on  the  scene  together  in  Miocene  times,  the 
world  having  got  along  without  both  before  that 
epoch.  This  entry,  hand  in  hand,  so  to  speak,  De 
Lapparent,  the  great  French  geologist,  does  not  hesi- 
tate to  link  logically,  and  to  regard  the  one  as  the 
necessary  complement  of  the  other.  If  this  were  not 
the  case,  there  is  certainly  no  reason  why  they  should 
appear  at  the  same  instant  of  time.  Food  evokes  its 
eater  in  fact  as  definitely  as  in  phraseology. 

The  last  of  this  procession  of  coincidences,  man, 
came  on  the  scene  at  the  time  when  the  cooling  of  the 
globe  rendered  his  own  extension  possible  at  the  least 
expense  to  himself.  His  brain  allowed  him  to  take 
advantage  of  conditions  less  intrinsically  favorable 
than  other  animals  could  endure.  His  mind  clothed 
his  body  and  gave  him  fire,  and  with  these  two  prod- 


THE    EVOLUTION   OF    LIFE  69 

ucts  he  sallied  forth  into  a  world  where  antagonists 
were  chiefly  climatic,  with  which  he  was  fitted  to  cope. 
Thus  all  along  the  line  we  perceive  that  life  and 
its  domicile  arose  together.  The  second  is  necessary 
to  the  first  and  the  first  is  always  sufficient  to  the 
occasion.  The  coincidence  of  the  possibility  and  its 
seizure,  of  the  posse  and  the  esse,  seems  to  be  a  gen- 
eral principle  of  evolution.  Endless  variation  is  con- 
stantly in  progress,  and  this  variation  takes  advantage 
of  any  opportunity  so  soon  as  it  occurs.  Life  but 
waits  in  the  wings  of  existence  for  its  cue,  to  enter 
the  scene  the  moment  the  stage  is  set. 


CHAPTER   III 

THE    SUN    DOMINANT 

Transition.  The  passing  of  the  supremacy  of  its  own  heat,  and 

the  entrance  of  the  Sun  upon  the  scene  as  the  dom- 
inant power  in  its  life,  mark  the  next  stage  in  a 
planet's  history. 

On  Earth  the  transition  from  self-support  to  solar 
dependence  began  with  the  first  symptoms  of  atmos- 
pheric clearing  in  the  time  of  the  great  reptiles.  The 
elouds  that  had  veiled  the  whole  Earth  in  the  paleo- 
zoic period  then  began  to  dissipate ;  though  it  was 
probably  not  until  much  later  that  the  sky  approached 
the  pellucid  character  we  know.  The  Earth's  own 
cooling  thus  first  let  in  the  Sun. 

That  such  must  have  been  our  Earth's  history  we 
gather  from  the  other  planets ;  that  it  actually  was  so 
we  discover  from  the  records  of  the  Earth  itself.  For 
from  the  fossils  embedded  in  its  rocks  we  learn  that 
when  the  Triassic  strata,  more  familiarly  known  as  the 
New  Red  Sandstone,  were  laid  down,  gymnosperms, 
cycads,  and  conifers  had  replaced  the  cryptogams  of 
the  primary  age.  These  plants  require  more  light 
than  ferns.  Though  technically  called  flowering 
70 


THE   SUN   DOMINANT  71 

plants,  they  yet  lacked  flowers  to  catch  the  eye.  Still, 
they  demanded  more  sunshine  than  their  predecessors, 
and  thus  testify  to  the  purifying  air  caused  by  the 
gradual  cooling  of  the  surface  and  the  consequent  less 
abundant  generation  of  cloud.  That  the  Sun  had  not 
grown  more  insistent,  but  the  Earth  more  open-eyed, 
the  latitudinal  character  of  the  cooling  shows.  For  it 
was  not  the  absolute  lowering  in  warmth,  but  the 
zonal  differentiation  of  temperature  that  then  set  in, 
which  is  the  noticeable  thing.  The  tropics  were  as 
before;  the  climate  was  changing  slowly  toward  the 
poles.  Climatic  zones  began  to  belt  the  Earth. 

In  the  next  mesozoic  division,  the  Jurassic,  the 
corals,  by  dropping  down  the  latitudes  as  time  went 
on,  speak  of  continued  refrigeration.  Tropic,  tem- 
perate, and  frigid  regions  began  to  belt  the  Earth. 
But  zones  were  not  yet  well  established,  as  the  pres- 
ence of  the  same  cycads  in  Mexico  and  Franz  Josef 
Land  suffices  to  attest.  Corals  still  grew  in  latitude 
55°  N. 

With  Tertiary  times  came  in  the  seasons.  Before  The  sun 
this  the  Earth  knew  them  not,  though  its  axial  tilt  was 
the  same  as  now.  Their  advent  is  registered  for  us 
in  the  changed  vegetation  they  induced.  For  their 
presence  is  witnessed  by  the  coming  in  of  deciduous 
trees,  which  make  their  first  appearance  in  its  preced- 
ing strata,  the  lower  Cretaceous,  and  spread  and 


72        MARS   AS   THE   ABODE   OF   LIFE 

flourished  in  the  Eocene,  Miocene,  and  Pliocene  eras. 
The  northern  zones  had  now  grown  so  cold  that  vege- 
tation had  to  hibernate  in  the  winter  months.  Mean- 
while we  mark  the  palms  successively  descend  the 
parallels  in  search  of  heat.  In  the  Eocene  —  the 
dawn  of  the  recent  —  already  they  are  lower  than  in 
earlier  epochs ;  in  the  Oligocene,  the  next  age,  their 
northern  limit  is  the  smaller  fifties ;  they  become 
rarer  there  in  the  Miocene ;  and  in  the  Pliocene  they 
have  virtually  disappeared  from  northern  Europe. 
With  increase  in  light  went  hand  in  hand  decrease  in 
warmth,  which  shows  that  the  Earth  had  been  the 
source  of  the  earlier  torrid  climate.  Its  seas  and  con- 
tinents were  both  cooling  off. 

The  Sun  was  slowly  asserting  his  position  as  the 
great  giver  of  both  light  and  heat,  and  the  world  as  we 
know  it  was  beginning  to  be.  I/ 

This  change  in  dependence  from  Mother  Earth  to 
distant  Sun  ushered  in  the  reign  of  beauty  in  the 
world.  We  live  in  the  colored  supplement  of  our 
globe's  history,  the  time  when  the  pigments  were  put 
on;  and  this  because  as  fashioner  the  Sun  has  replaced 
the  Earth.  Though  they  bear  no  relation  to  us,  the 
gorgeous  tints  of  blossom,  butterfly,  and  bird  that  so 
delight  the  eye  were  called  into  being  by  the  sunbeams 
themselves ;  while  the  descendants  of  the  plants  that 
were  beholden  chiefly  to  the  Earth  — the  fungi,  mosses, 


THE    SUN    DOMINANT  73 

and  brakes  —  are  sombre  browns  and  greens,  and 
flourish  only  in  the  shade.  A  few  indeed  have 
adapted  themselves  to  the  new  conditions,  but  the 
greater  part  still  pathetically  cling  to  the  world  in 
which  they  were  brought  up  —  a  world  (except  in 
corners)  long  since  passed  away. 

Since  a  general  clearing  of  its  sky  is  a  regular  step  Mars  betray* 
in  a  planet's  development,  we  should  expect  to  find  a  ^^ 
cloudless,  transparent  air  "in  the  case  of  a  planet  as 
relatively  old  as  Mars.  For  thus  a  body  opens  its 
eyes  to  the  cosmos.  Now,  this  is  precisely  what  we 
do  find.  The  aspect  of  Mars  shows  that  it  has  thus 
waked  to  the  universe  about  it.  In  fact,  such  was  the 
very  first  of  its  characteristics  to  be  made  known  to 
the  earth,  being  the  one  by  which  the  others  were  re- 
vealed. Without  it  we  had  never  made  acquaintance 
with  this  other  world  in  space. 

Viewed  under  suitable  conditions,  few  sights  can 
compare  for  instant  beauty  and  growing  grandeur  with 
Mars  as  presented  by  the  telescope.  Framed  in  the 
blue  of  space,  there  floats  before  the  observer's  gaze  a 
seeming  miniature  of  his  own  Earth,  yet  changed  by 
translation  to  the  sky.  Within  its  charmed  circle  of 
light  he  marks  apparent  continents  and  seas,  now  ram- 
ifying into  one  another,  now  stretching  in  unique  ex- 
panse over  wide  tracts  of  disk,  and  capped  at  their 
poles  by  dazzling  ovals  of  white.  It  recalls  to  him 


74        MARS   AS   THE   ABODE   OF   LIFE 

his  first  lessons  in  geography,  where  the  Earth  was 
shown  him  set  ethereally  amid  the  stars,  only  with  an 
added  sense  of  reality  in  the  apotheosis.  It  is  the 
thing  itself,  stamped  with  that  all-pervading,  indefin- 
able hall-mark  of  authenticity  in  which  the  cleverest 
reproduction  somehow  fails. 

In  color  largely  lies  this  awakening  touch  that  im- 
bues the  picture  with  the  sense  of  actuality.  And 
very  vivid  are  the  tints,  so  salient  and  so  unlike  that 
their  naming  in  words  conveys  scant  idea  of  their  con- 
cord to  the  eye.  Rose  ochre  dominates  the  lighter 
regions,  while  a  robin's-egg  blue  colors  the  darker  ; 
and  both  are  set  off  and  emphasized  by  the  icy  white- 
ness of  the  caps.  Nor  is  either  hue  uniform ;  tone 
relieves  tint  to  a  further  heightening  of  effect.  In 
some  parts  of  the  light  expanses  the  ochre  prevails 
alone  ;  in  others  the  rose  deepens  to  a  brick-red,  suf- 
fusing the  surface  with  the  glow  of  a  warm,  late  after- 
noon. No  less  various  is  the  blue,  now  sinking  into 
deeps  of  shading,  now  lightening  into  faint  washes  that 
in  places  grade  off  insensibly  into  ochre  itself,  thus 
making  regions  of  intermediate  tint  the  precise  borders 
of  which  are  not  decipherable  by  the  eye. 

Superimposed  upon  its  general  opaline  complexion 
are  now  and  then  to  be  seen  ephemeral  effects.  At 
certain  times  and  in  certain  places  warm  chocolate- 
brown  has  been  known  to  supplant  the  blue.  Often, 


."« 


v 


' 


THE    SUN   DOMINANT  75 

too,  cold  white  dots  are  scattered  over  the  disk,  daz- 
zling diamond  points  that  deck  the  planet's  features 
to  a  richness  beyond  the  power  of  pencil  to  portray. 
So  minute  are  they  that  good  seeing  is  needed  to  dis- 
close them.  It  is  at  such  moments  that  color  best 
comes  out.  To  those  who  know  the  sun  only  as 
golden  and  the  moon  as  white,  even  in  its  color 
scheme  Mars  would  stand  forth  a  revelation. 

It  is  easy  to  travel  in  thought  over  the  strange 
land  thus  displayed  below  you.  For  though  you 
gaze  up  into  the  sky,  you  still  look  down  upon  its 
ground,  and  follow  consciously  or  unconsciously  the 
configuration  of  its  surface  with  cartographic  eye,  now 
led  by  some  apparent  bay  to  run  with  it  up  into  the 
continent,  now  witched  by  the  spirit  of  exploration 
toward  some  island,  as  it  seems  to  be,  set  remote  in 
the  midst  of  the  sea.  But  whether  you  purpose  it  or 
not,  nature,  taking  the  matter  out  of  your  hand,  de- 
cides it  for  you.  For  presently  you  perceive  your 
point  of  view  not  to  be  quite  what  it  was.  The  bay 
in  question,  as  well  as  the  island,  has  slightly  changed 
its  place  upon  the  disk,  while  the  two  have  kept  their 
mutual  relation  unaltered.  A  few  minutes  more  and 
the  shift  has  increased,  and  then  you  become  aware 
of  what  is  taking  place  :  this  other  world  is  turning  on 
itself,  as  turns  our  own,  rotating  from  west  to  east  as 
it  rolls  along  its  orbit  about  the  sun. 


76        MARS   AS   THE   ABODE   OF   LIFE 

Up  over  the  rim  of  the  disk  rises  a  marking,  to 
swing  in  time  across  the  centre,  and  then  on  out  of 
sight  round  the  other  limb.  The  one  horizon  marks 
the  sunrise-line  upon  the  planet,  the  other  the  sunset 
one,  and  in  its  course  between  the  two  the  place  has 


Two  VIEWS  OF  THE  SOLIS  LACUS  REGION  OF  MARS,  ONE  HOUR  APART, 
JULY  26,  1907  (THE  ONE  TO  THE  LEFT  THE  EARLIER),  SHOWING  THE 
ROTATION  OF  THE  PLANET.  NORTH  is  AT  THE  TOP 

had  its  Martian  day.  Unsuspectedly,  but  no  less 
potently  for  that,  the  act  of  such  withdrawal  only  whets 
curiosity  the  more.  What  perchance  might  have 
wearied  had  it  remained  forever  there,  gains  an  added 
glamour  from  the  fact  that  it  is  gone.  But,  more  than 
this,  it  gives  an  earnest  of  yet  further  fields  to  be 
explored.  From  the  circumstance  of  turning  comes 
promise  that  other  regions  will  later  be  displayed,  and 
as  the  observer  watches,  the  predicted  comes  to  pass. 
One  longitude  after  another  turns  the  corner,  rounds 
into  view,  and  slowly  swings  into  the  meridian  plane. 


THE    SUN   DOMINANT  77 

Objects,  grown  familiar,  give  place  to  others  that  are 
new.  Sitting  alone  in  midnight  vigil  in  his  silent 
dome,  the  astronomer  thus  mutely  circumnavigates 
another  world. 

The  cloudlessness  of  the  planet's  sky  alone  makes 
such  travel  possible.  Were  it  not  for  the  unobstructed 
view,  exploration  of  the  sort  would  be  out  of  the  ques- 
tion. Were  Mars  not  an  old  planet,  corroborating  by 
absence  of  cloud  the  general  course  of  planetary  devel- 
opment, our  knowledge  of  it  had  been  slight.  To 
begin  with,  its  lack  of  covering  enables  us  to  mark 
the  permanency  in  place  of  the  planet's  features,  and 
from  such  permanently  to  time  the  planet's  axial 
rotation.  This  gives  us  knowledge  of  the  planet's 
day  and  furnishes  means  to  measure  it.  This  day 
proves  to  differ  in  duration  little  from  our  own, 
being  24  hours,  40  minutes  long,  instead  of  24 
hours.  In  the  next  place  its  scantiness  of  atmos- 
pheric apparel  discloses  the  tilt  of  the  axis  to 
the  planet's  orbital  plane,  a  relation  which  causes 
the  seasons  of  the  year.  Now  the  Martian  tilt, 
as  well  as  the  Martian  time  of  rotation,  turns 
out  to  be  singularly  like  our  own,  being,  in  fact, 
24°  *  as  against  23  J°  for  the  Earth.  Thus  the 
Martian  seasons  counterpart  ours.  The  year  of 

*  Still  later  measures  at  Flagstaff  make  this  even  smaller,  23°  13',  —  or  actually  a 
little  less  than  ours.  (See  note  18. ) 


78        MARS   AS   THE   ABODE   OF   LIFE 

Mars,  however,  is  twice  ours  in  length,  which,  joined 
to  great  eccentricity  of  orbit,  gives  it  diversifiedly  long 
seasons.  Thus,  in  the  northern  hemisphere,  spring 
lasts  199  days,  summer  183,  autumn  147,  and  winter 
158,  while  in  its  southern  hemisphere  the  figures  stand 
reversed.  The  numbers  have  more  than  academic 
importance,  for  absolute  length  is  as  vital  a  factor  in  a 
season's  influence  as  the  fact  of  the  season  itself. 
Much  maybe  brought  to  pass  in  twice  the  time  which 
could  not  develop  in  the  shorter  period.  And  it  is 
not  a  little  interesting  that  precisely  this  possibility 
actually  turns  out  to  be  vital  in  the  vegetative  economy 
of  the  planet's  year. 

Absence  of  cloud  speaks,  too,  of  the  thinness  of 
the  planet's  air,11  of  which  we  have  other  evidence  as 
well.  Perhaps  the  best  proof  of  a  relatively  thin  air 
is  the  lack  of  intrinsic  brilliancy  of  the  Martian  disk, 
its  "albedo,"  as  it  is  called.  This  is  only  27  per  cent  of 
absolute  reflection,  as  against  92  per  cent  for  Venus. 
Now,  a  thick  air,  even  if  clear,  —  indeed,  because  clear, 
—  would  cast  a  luminous  veil  over  the  planet's  face 
due  to  dust  or  vapor,  as  it  does  with  Venus,  dimming 
its  features.  Such  is  not  the  case  with  Mars. 

Of  twilight,  therefore,  there  should  be  less,  and 
certain  observations  made  at  Flagstaff  in  1894  seem  to 
prove  this.  The  refractive  medium  of  air  which  on 
Earth  calls  the  Sun  earlier  in  the  morning,  and  keeps 


THE   SUN   DOMINANT 


THE  NORTH  POLAR  CAP  OF  MARS  AT  ITS  LEAST  EXTENT 

him  up  later  at  night  than  would  otherwise  be  the 
case,  is  not  so  potent  on  Mars.  Day  there  enters  with 
greater  abruptness,  and  lapses  into  more  sudden  dusk. 
Then  comes  a  night  when  the  stars  stand  forth  with 
an  insistency  unknown  on  earth. 

That  some  air  exists  is,  however,  patent,  both  directly 
from  the  limb-light  that  fringes  the  circlet  of  the  disk 


8o       MARS   AS   THE   ABODE   OF   LIFE 

and  inferentially  from  the  changes  that  we  mark  in 
progress  on  the  planet's  face.  For  change  of  itself 
implies  an  atmosphere. 

The  polar  First  of  the  phenomena  to  betray  this  air  were  the 

-caps  of  Mars,   ^j^  caps  tnat  bonnet  the  Martian  poles;  for  in  the 

person  of  these  patches  transformation  was  first  recorded 
upon  the  Martian  disk.  Their  position,  together  with 


THE  SOUTH  POLAR  CAP  OF  MARS  AT  ITS  GREATEST  EXTENT 


THE   SUN   DOMINANT 


81 


th^ir  seasonal  wax  and  wane,  pointed  them  out  for 
polar  snows  gathered  during  the  Martian  winter  and 
melting  with  the  Martian  spring. 

That  the  polar  caps  are  composed  of  snow,  or^ 
rather,  hoar-frost,-  suggests  itself  to  any  one  who 
carefully  scans  the  planet.  But  to  prove  it  was  not 
so  easy.  Fortunately, 
a  phenomenon  which 
accompanies  it  turned 
out,  when  rightly 
reasoned  on,  a  touch- 
stone to  its  character. 
As  the  cap  melts,  it 
is  seen  to  be  girdled 
about  by  a  dark-blue 
band,  deeper  in  tone 
than  any  other  blue- 
green  area  on  the  disk.  This  belt  developed  the 
peculiar  property  of  retreating  with  the  cap  as  the 
latter  shrank,  maintaining  throughout  its  attendant 
post.  The  phenomenon  was  first  seen  by  Beer  and 
Madler,  but  it  was  not  till  1894  that  its  significance 
was  seized. 

Clearly  the  outcome  of  the  melting  cap,  it  disposed 
by  that  fact  of  the  suggestion  that  the  caps  might  be 
solid  carbonic  acid  that  freezes  at  109°  F.  into  a  sub- 
stance not  unlike  snow.  For  carbonic  acid,  under 


DRAWING  OF  MARS,  APRIL  8,  1907, 
SHOWING  THE  DARK  BELT  THAT  GIR- 
DLES THE  SNOW  DURING  ITS  MELTING 


8z        MARS   AS   THE   ABODE   OF   LIFE 

pressures  of  one  atmosphere,  or  less,  such  as  would  be 
the  case  on  Mars,  passes  instantly  from  the  gaseous 
into  the  solid  state.  Not  so  water-vapor.  Here, 
then,  was  a  telltale  bit  of  behavior.  The  blue  belt 
proclaimed  the  presence  of  a  liquid.  Thus  carbonic 


From  drawings,  July  20  and  22,  before  and  after  the  event. 
EARLY  WINTER  SNOW-STORM  IN  THE  NORTHERN  HEMISPHERE  OF  MARS, 
1907  (NORTH  AT  THE  BOTTOM).      MARTIAN  DATES  :  OCTOBER  22,  LEFT- 
HAND  DRAWING;  OCTOBER  23,  RIGHT-HAND  DRAWING 

acid  could  not  be  concerned,  and  the  substance  com- 
posing the  caps  was  therefore  snow.  For  no  other, 
that  we  know  of,  dons  their  snowy  aspect  with  change 
of  state. 

The  behavior  of  the  cap  thus  affords  intrinsic  proof 
of  its  constitution.  Since  this  was  determined,  another 
line  of  argument  has  given  extrinsic  evidence  of  the 
same  thing.  This  is  the  evaluation  of  the  surface 
temperature  of  the  planet  recently  made  for  the  first 
time  with  any  approach  to  precision. 


THE    SUN   DOMINANT  83 

The  stronghold  of  doubt  as  to  the  habitability  of  The  question 
Mars  has  always  been  the  difficulty  of  accounting  for  ^^^ 
a  temperature  there  high  enough  to  support  life. 
From  its  own  bodily  heat  at  the  present  time  the 
t  itself,  like  our  own  earth,  can  contribute  to  the 
surr.-e  temperature  no  appreciable  amount.  The 
necess;r.  y  caloric  must  all  come  from  the  sun.  Now, 
because  the  planet  was  half  as  far  again  from  the  sun 
as  the  earth,  and  because  light  and  heat  diffuse  in- 
versely as  ti;-  square  of  the  distance,  —  a  candle  two 
feet  away  giving  only  one-fourth  the  light  of  one  a 
foot  off,  —  it  was  suppc  that  Mars  must  receive 
only  four-ninths  the  warmth  that  the  earth  gets,  which 
would  render  its  temperature  terribly  low. 

But  the  receipt  of  radiant  energy  is  not  so  forth- 
right as  this.  To  begin  with,  the  bundle  of  rays  from 
the  sun  striking  the  planet  is  subject  to  two  adventures 
at  the  very  threshold  of  its  planetary  career.  A  part 
of  it  is  at  once  reflected  back  into  space  from  the  body 
it  strikes  —  from  the  air  first,  then  from  the  planetary 
surface.  But  the  reflected  light  or  heat  does  not  go  to 
warm  the  body  at  all.  Strange  to  say,  this  important 
fact  had  never  been  taken  into  account  until  the 
present  investigation  of  the  subject,  which  led  to  a 
completely  different  outcome  from  what  had  previously 
been  supposed.  Too  technical  for  exposition  here, 
one  or  two  points  in  it  may  be  mentioned.  First,  the 


84        MARS   AS   THE   ABODE   OF   LIFE 

proportionate  amount  of  the  reflected  light-rays  which 
reach  an  observer  stationed  on  another  planet  measures 
the  relative  brightness  of  that  planet  as  seen  by  him. 
This  per  cent  per  square  unit  of  surface  at  distance 
unity  is  what  is  called  the  planet's  albedo.  Now  the 
albedo  of  the  different  planets  has  been  found  by  more 
than  one  observer  from  investigations  unconcerned 
with  our  present  subject,  the  only  gap  in  the  series 
being  that  of  our  own  earth.  The  latest  determina- 
tion by  Miiller  is  :  — 

Mercury 0.17 

Venus 0.92 

Mars 0.27 

Jupiter 0.75 

Saturn  (Struve) 0.78 

Uranus 0.73 

Neptune 0.63 

Our  own  earth's  albedo  is  lacking  from  the  table 
because  we  cannot  see  ourselves  as  others  see  us,  and 
are  consequently  somewhat  in  the  dark  as  to  our  own 
appearance.  By  suitable  deduction,  however,  from  the 
brightness  of  sunlight  at  different  altitudes  above  the 
surface  of  the  earth,  it  is  possible  to  get  some  idea  of 
it,  and  from  this  a  modest  estimate  puts  it  as  at  least 
.75.  So  that  we  are  not  so  dull  as  we  thought. 

Thus  we  get  the  amount  of  radiant  energy  received 


THE   SUN   DOMINANT  85 

from  the  visible  part  of  the  sun's  rays.  There  are  also 
rays  too  long  to  be  perceived  by  our  eyes,  and  these 
must  also  be  considered  in  a  determination  of  the 
whole.  The  bolometer  invented  by  Langley  enables 
us  to  do  this,  and  so  to  obtain  the  fraction  of  the 
total  incident  energy  which  goes  to  warm  the  body. 

£^' 

In  the  case  of  the  earth  it  proves  to  be  41  per  cent 
of  the  whole ;  and  in  the  case  of  Mars,  60  per  cent. 
Here,  then,  we  have  at  once  a  serious  modification 
of  a  calculation  based  on  distance  alone. 

But  this  is  not  all.  The  clearness  of  the  Martian  The  clear 
sky  comes  in  to  abet  the  greater  transmission  of  its  skiesofMars- 
air.  From  dawn  till  dusk,  day  after  day  in  the  sum- 
mer season,  and  largely  in  winter,  the  sun  shines  out 
of  a  heaven  innocent  of  cloud.  No  shield  of  the 
sort,  and  only  a  little  screen  of  air,  tempers  its 
beams  to  the  soil  held  up  to  it.  Such  an  exposure 
far  exceeds  anything  we  have  on  earth ;  for  with  us, 
even  in  the  tropics,  clouds  gather  as  soon  as  the 
heating  grows  excessive,  and  cool  the  air  by  plumps 
of  rain. 

How  much  this  means  to  a  planet  as  far  away 
from  the  sun  as  Mars,  will  appear  if  we  consider 
what  in  this  respect  is  the  condition  of  the  earth. 
Over  the  earth  as  a  whole,  the  proportion  of  actual 
to  possible  sunshine  for  the  whole  year  is  50  per 
cent.  That  is,  the  sky  is  such  that  the  sun  shines 


86        MARS   AS   THE   ABODE   OF   LIFE 

only  half  the  time  it  might  were  there  no  clouds  to 
screen  it. 

On  Mars  the  spring  mistiness  at  the  borders  of 
the  polar  cap  is  the  only  veiling  the  surface  knows, 
with  the  result  that  the  percentage  of  sunshine 
throughout  the  year  is  99  per  cent  of  the  utmost 
possible.  This  is  somewhat  reduced  by  the  fact 
that  some  light  and  heat  of  course  is  let  in  by  the 
clouds  —  and  is  kept  in  better,  too. 

Taking  these  different  data,  and  using  the  most 
recently  determined  relation  of  radiation  to  temper- 
ature (that  of  Stefan,  which  has  been  independently 
deduced  theoretically  by  both  Boltzmann  and  Ga- 
litzine),  we  find  that  the  mean  temperature  of  the 
surface  air  of  Mars  should  be  about  48°  F.  We 
must  not  place  too  much  credence  in  the  actual  fig- 
ures, for  our  knowledge  of  the  laws  of  atmospheric 
retention  of  heat  is  very  uncertain,  but  the  research 
is  enough  to  show  that  the  above  result  is  much 
nearer  the  truth  than  the  terribly  cold  ones.  That 
of  the  earth  is  only  60°  F. ;  so  that  the  mean  cli- 
matic warmth  of  the  two  planets  is  not  very  unlike, 
and  far  within  the  possibilities  of  life  for  both.1'2 

But  the  circumstances  are  even  more  favorable  to 
Martian  life  than  this.  For  man  does  not  live  by 
mean  annual  temperatures  alone.  In  fact  neither 
he  nor  other  animals  in  our  temperate  zones  pay  so 


THE    SUN   DOMINANT  87 

much  heed  to  yearly  averages  as  is  sometimes  sup- 
posed. Much  more  to  the  point  with  them  is  the 
mean  summer  warmth  they  experience. 

Now,   in    the  summer-time,  —  that  is,  all    the  way  Summer  and 
from  some  months  after  the  winter  solstice  to  some 

peratures. 

months  after  the  summer  one,  —  more  heat  is  ab- 
sorbed daily  from  the  sun  than  is  radiated  out  to 
the  stars  at  night.  The  surface  temperature  is  then 
constantly  rising ;  a  fact  patent  when  one  stops  to 
think  of  it  in  this  way,  since  June  is  warmer  than 
March,  but  that  this  means  that  the  day's  gain  ex- 
ceeds the  night's  loss  is  commonly  lost  sight  of. 
The  fact  is  pertinent  to  our  present  inquiry.  For 
the  daily  increment  continues  for  half  the  year,  and 
the  Martian  year  is  twice  our  own  in  length.  Its 
total  gain  in  summer  over  the  mean  would,  other 
things  equal,  rise  to  something  like  twice  our  own. 
Instead  of  a  temperature  lift  of  30°,  as  with  us,  on 
Mars  it  might  well  be  50°,  in  spite  of  the  thinner  air. 
That  a  thin  air  is  compatible  with  great  surface 
heat  the  latest  and  most  authoritative  measures  of 
the  heat  of  the  moon's  surface  during  the  lunar  day 
interestingly  corroborate.  These  measures  are  those 
of  Professor  Very.  With  great  care  and  thorough- 
ness this  excellent  investigator  experimented  on  the 
amount  of  heat  radiated  by  different  parts  of  the 
moon  at  different  times  of  the  lunar  day.  He  con- 


88        MARS   AS   THE   ABODE   OF   LIFE 

tinued  the  work  Langley  had  begun  to  a  much 
finer  point  of  precision.  It  used  to  be  thought  that 
even  at  lunar  midday  the  temperature  of  the  moon's 
surface  must  be  below  freezing  because  of  its  lack  of 
a  retaining  blanket  of  air.  Very's  latest  conclusions 
in  the  matter  put  a  quite  different  aspect  upon  it. 
In  a  letter  of  his  to  the  writer  he  sums  up  his  results 
as  follows  :  — 

When  the  sun  rises,  no  matter  in  what  latitude,  it  is  cold.  I  do 
not  venture  to  say  how  cold,  but  below  the  freezing-point.  Not 
until  the  sun  has  reached  an  altitude  of  I  5°  in  middle  latitudes  does 
the  temperature  get  above  freezing.  Then  the  heat  mounts  rapidly 
until  at  the  end  of  the  first  week  of  sunshine  in  dry  regions  near  the 
equator  the  rock  surface  is  as  hot  as  boiling  water.  As  midday  ap- 
proaches at  the  end  of  the  second  week,  the  scorching  rocks  attain 
a  temperature  full  80°  centigrade  above  the  boiling-point  of  water 
in  regions  under  a  vertical  sun  (356°  F. ).  Having  once  become 
heated,  the  rocky  surface  retains  its  heat  to  a  great  extent  far  into  the 
afternoon,  the  curve  of  falling  temperature  being  perhaps  a  day  and 
a  half  of  our  time  out  of  symmetry.  Toward  the  end  of  the  lunar 
afternoon  the  fall  of  temperature  is  very  rapid,  and  before  the  sun 
sets,  frost  prevails,  or  at  least  temperatures  which  produce  frost 
wherever  there  is  water-vapor  to  make  the  article  which  we  call 
"  hoar-frost." 

And  this  great  heat  occurs  where  there  is  virtually 
no  blanket  of  air ;  and,  what  is  even  more  striking, 
its  temperature  maximum  is  not  attained  till  a  day 
and  a  half  after  its  greatest  receipt  of  sunshine. 


THE   SUN   DOMINANT  89 

Now,  when  we  turn  from  deduction  to  the  picture  Aspect  of 
the  planet  presents,  which,  after  all,  is  entitled  to  corroborative, 
some  consideration  in  statements  about  itself,  we 
confront  what  certainly  seems  a  body  in  fairly  easy 
circumstances  of  temperature.  In  its  summer  the  sur- 
face lies  fully  exposed  to  our  gaze,  and  it  assuredly 
is  not  suffering  from  wholesale  glaciation.  On  the 
contrary,  the  phenomena  point  to  something  quite 
the  reverse.  For  weeks  its  arctic  regions  up  to  86° 
and  87°  N.  latitude  are  certainly  above  the  freezing- 
point,  since  the  snow  disappears.  Probably  they  are 
far  above  it,  for  in  the  polar  caps  we  then  behold  a 
shrinkage  much  greater  than  anything  we  similarly 
experience  on  earth,  part  of  which  is  due  to  less 
depth  of  snow,  but  showing  also  that  it  is  relatively 
warmer  there  than  here.  Lower  down  the  disk, 
toward  the  equator,  great  dust-storms,  like  the  si- 
mooms of  our  Sahara,  sweep  over  portions  of  it  at 
times,  hundreds  of  square  miles  in  extent,  convey- 
ing to  the  onlooker  anything  but  a  sense  of  chill.13 

In  winter  the  opposite  state  of  things  prevails.  A 
good  sixth  of  the  whole  surface  goes  into  winter 
quarters  as  each  autumn  draws  on.  It  stays  so,  too, 
for  some  eight  of  our  months  on  end,  not  to  emerge 
till  the  next  Martian  spring.  A  winter  on  Mars  in 
high  latitudes  has  a  polar  complexion  to  it  not  wholly 
pleasing  to  contemplate. 


9o       MARS   AS   THE   ABODE   OF   LIFE 

But  the  idea  that  such  a  winter's  counterpane  be- 
tokens more  than  hibernation,  and  in  any  sense  hazards 
the  existence  of  life,  a  moment's  thought  on  our  own 
conditions  of  living  will  suffice  to  dispel.  The  great 
nations  of  the  earth,  with  scarce  an  exception,  live  half 
the  year  in  the  earth's  north  polar  cap,  buried  in  snow 
and  hidden  the  greater  part  of  the  time  from  visual 
communication  with  outside  space.  If  Martian  phi- 
losophers are  of  the  pattern  of  some  earthly  ones,  they 
must  incontrovertibly  prove  to  their  own  satisfaction 
the  impossibility  of  our  existence.  Nevertheless,  from 
the  fairly  successful  way  in  which  we  manage  to  sur- 
vive in  open  contravention  of  philosophy,  we  see  that 
it  is  not  necessary  even  to  suppose  hibernation,  fea- 
sible as  nature  finds  that  to  be  with  insects,  fishes,  and 
beasts,  in  order  to  tide  an  animal  over  from  one  period 
of  warmth  to  the  next.  An  organism  with  or  without 
what  we  are  pleased  to  call  human  intelligence  is  quite 
capable  of  submitting  to  conditions  which  would,  if 
permanent,  prove  destructive  to  life,  and  of  biding  its 
time  to  a  more  propitious  season. 

Summer  the  For,  thanks  to  recent  research,  we  now  know  that 
with  animals  generally  it  is  the  summer  temperature, 
not  the  winter  one,  that  decides  the  question  as  to 
whether  life  shall  exist.  An  able  investigation  of  the 
United  States  Government  Zoologist,  Dr.  Merriam, 
made  upon  the  region  of  the  San  Francisco  peaks,  in 


THE   SUN   DOMINANT 


91 


;;;:]TIMBER  LINE  ZONE   ^^^DOOatAS  FIR  ZONE  PINON  ZONE 

_SPRUCEZONE        [ ]  PINE  ZONE          1 1||  |  1 1|  1 1  DESERT 

MERRIAM'S  MAP  OF  SAN  FRANCISCO  MOUNTAIN  AND  VICINITY,  ARIZONA 
Published  in  "  North  American  Fauna,  No.  3." 


92       MARS   AS   THE   ABODE   OF   LIFE 

1889,  brings  this  point  out  with  great  acumen.  Its 
pertinency  to  the  problem  before  us  commends  it  to 
reference  here. 

In  geographic  and  climatic  position  combined  the 
San  Francisco  Mountains  of  northern  Arizona  are 
among  the  most  interesting  animal  and  vegetal  habitats 


of  the  globe.  They  are  what  is  left  of  a  great  crater  of 
Tertiary  times,  which,  rising  out  of  the  plateau  north 
of  the  Arizonian  desert,  tower  to  12,630  feet  of  alti- 
tude. The  massif  of  this  once  volcanic  cone  sup- 
ports now  many  square  miles  of  forest  on  its  flanks, 
and  its  plateau  base  is  clothed  with  pine  ;  while  girdling 
it  about,  and  cutting  it  off  like  an  island  from  other 


THE   SUN    DOMINANT 


93 


vegetation,  stretch  the  arid  wastes  of  the  great  Ameri- 
can desert. 

This  floral  island  is  remarkable  for  being  banded  by  Zonesofvege- 
successive  zones  of  trees,  each  distinctive  and  exclusive,  ^F^J^ 
and  giving  place  the  one  to  the  other  solely  according  Mountains. 


ARIZONA  DESERT  VIEW 


to  elevation.  Starting  from  the  desert  forty  miles 
away,  where  sage-brush  and  cacti  alone  succeed  in 
managing  an  existence,  the  traveller  enters  at  an  eleva- 
tion of  a  mile  and  a  quarter  above  the  sea  the  initial 
zone  of  scrub.  Stunted  at  first,  clumps  of  dwarf  juni- 
per—  cedars,  as  they  are  locally  called  —  make  their 
appearance,  and  grow  in  size  and  vigor  as  he  continues 


94       MARS   AS   THE   ABODE   OF   LIFE 

to  ascend.  With  them  are  soon  associated  another 
form  of  juniper  and  the  pinon,  a  small  tree  from  twenty 
to  thirty  feet  in  height.  At  about  7000  feet  he  en- 
counters the  Pinus  ponderosa,  to  which  the  juniper  and 
pinons  then  give  way,  and  the  whole  aspect  of  the 


THE  DOUGLAS  FIR 

tree  vegetation  changes.  Here  the  stately  pines  pos- 
sess the  land  alone,  save  for  a  few  white  oaks  on  the 
edges  of  the  mesas.  At  8500  feet  the  yellow  pines 
disappear,  to  be  succeeded  by  the  Douglas  fir,  the 
Rocky  Mountain  pine,  and  the  beautiful  trembling 
aspen.  At  9500  feet  this  set  of  trees  gives  place  to 
yet  another,  and  the  traveller  enters  the  western  white 
spruce  zone,  associated  with  which  is  the  fox-tail  pine, 


THE    SUN    DOMINANT  95 

the  needles  of  which  startlingly  suggest  a  fox's  brush. 
At  10,500  feet  these  trees  dwindle  to  dwarf  specimens 
of  themselves,  until  at  12,000  feet  they  entirely  lapse, 
and  naked  rock  stretches  supreme  to  the  summit.  A 
climb  of  8000  feet  from  5000  to  13,000  of  elevation 
has  carried  the  observer  through  six  zones  of  absolutely 
distinct  tree  life,  counterparts  of  the  tropic,  the  tem- 
perate, the  Canadian,  the  Hudsonian,  the  Arctic,  which 
he  would  have  traversed  had  he  journeyed  from  the 
foot  of  the  mountains  northward  to  the  pole. 

To  the  higher  slopes  of  the  mountain  every  summer 
deer  troop  from  the  lower  plateaux  where  they  have 
passed  the  winter,  to  stay  at  these  heights  until 
October's  cold  drives  them  down  again  ;  while  upon  it 
all  the  year  round  are  to  be  found  bear,  which  also  go 
up  and  down  with  the  change  in  seasons.  In  addition 
to  these  are  wildcats  and  mountain  lion,  besides  a 
host  of  smaller  mammals,  squirrels,  gophers,  and  the 
like. 

Merriam  camped  upon  the  peak  in  July,  1889,  and  Summer 
studied  the  habits  of  the  animals  at  high   elevations 
during  the  summer  months,    comparing   the    various  ufe- 
genus    and    species    found    there   with    those    known 
northward  in  the  world.     Among  other  interesting  re- 
sults he  found  that  the  survival  of  species  is  determined 
not  by  the  mean  annual  temperature  of  the  locality  or 
by  the  winter  minimum,  but  by  the  maximum  temper- 


96        MARS   AS   THE   ABODE   OF   LIFE 

ature  prevailing  during  the  short  summer  months.  It 
is  in  this  season  that  the  animals  bring  forth  their 
young,  and  his  study  showed  that  if  they  were  suffi- 
ciently warm  during  the  reproductive  season,  cold  dur- 
ing the  rest  of  the  year  mattered  not.  At  the  worst 
they  hibernated.  Here,  then,  the  fact  of  a  few  warm 
weeks  made  life  possible,  outweighing  the  impossibility 
of  all  the  other  long,  cold,  forbidding  months.  Fur- 
thermore, what  is  important  to  our  present  discussion, 
Merriam  found  that  temperature  was  more  potent  than 
humidity,  so  long  as  they  had  any  water  at  all. 

This  point  in  animal  history  has  immediate  bearing 
upon  the  habitability  of  Mars ;  for  the  Martian  sum- 
mer is  twice  as  long  as  ours,  and,  as  we  have  seen,  the 
probable  acme  of  warmth  attained  in  it  is  by  no  means 
small.  It  is  by  these  attributes  of  its  climate,  and 
not  by  its  mean  annual  temperature,  or  by  the  great 
cold  its  surface  very  possibly  experiences  in  winter, 
that  its  ability  to  support  life  must  be  judged. 

Another  point  the  presence  of  the  animals  on  the 
San  Francisco  Mountains  serves  to  bring  out  —  their 
indifference  to  thinness  of  the  air.  The  creatures 
which  dwell  on  the  peak,  or  which  visit  it  as  a  summer 
resort,  are  members  of  the  same  species  whose  natural 
home  is  at  sea-level  farther  north.  The  deer  are  such 
as  one  finds  in  the  northern  part  of  the  United  States  ; 
the  bear  are  the  same  as  those  inhabiting  the  forests  of 


THE   SUN   DOMINANT  97 

Canada  and  Labrador.  Altitude  takes  the  place  of 
latitude  in  sufficiently  cooling  the  habitat  to  their  ac- 
commodation. But  it  does  this  at  the  expense  of  air. 
On  the  peak  they  dwell  at  elevations  of  10,000  feet, 
where  the  barometer  marks  only  18  inches,  instead  of 
the  30  to  which  their  relatives  are  accustomed.  Yet, 
in  spite  of  living  in  atmospheric  penury  on  the  man- 
sard roof  of  the  world,  —  for  the  mountain  here  is 
steep,  —  they  suffer  no  inconvenience,  and  seem  totally 
unaware  that  they  are  doing  anything  peculiar.  Nor 
have  they  seemingly  changed  in  organic  or  even  in 
functional  development.  With  the  deer  the  lack  of 
special  adaptation  is  equaled  only  by  the  lack  of  con- 
scious absence  of  it,  and  the  animal  is  as  much  at  home 
as  in  the  timber  of  the  Minnesota  woods. 

That  thinning  of  the  air  proves  no  bar  to  a  species, 
provided  other  conditions  are  the  same,  is  further 
shown  on  the  high  lands  of  the  western  United  States. 
The  meadow-larks  of  the  great  plains  rise  with  the 
surface  into  the  parks  of  the  Colorado  Rockies,  with 
an  altitude  of  eight  thousand  feet,  and  are  there  as 
much  acclimated  as  at  two  thousand  in  the  Kansas 
prairies. 

Now,  if  such  a  barometric  range  can  be  borne  semi- 
annually  without  special  modification  by  the  organism, 
how  much  more  may  not  be  accomplished  by  accom- 
modation, given  a  sufficiency  of  time  ?  Men  who  first 


98        MARS   AS   THE   ABODE   OF   LIFE 


pitiably  gasp,  learn  to  endure,  and  finally,  embrace,  a 
life  of  elevation.  Quito,  at  ten  thousand  feet,  has  a 
population  who  live  as  easily  as  their  relatives  at  sea- 
level. 

Owing  to  the  thinness  of  the  air,  it  has  been  cus- 
like elevation,  ternary  to  liken  the  conditions  on  Mars  to  those  upon 


Plateaux 
hotter  than 
peaks  at  a 


HIMALAYA. 


^atitude.  29°  North  Latitude,  i63  South  Latitude. 

From  Geikie's  "  Elementary  Lessons  in  Physical  Geography."     (The  Macmillan 
Company.) 

VERTICAL  DISTRIBUTION  OF  CLIMATE  ON  MOUNTAINS,  SHOWING  HOW 
LAND-MASSES  RAISE  THE  TEMPERATURE 

our  highest  mountain  tops,  where  life  finds  it  impos- 
sible to  exist.  But  the  analogy  is  misplaced.  Mars, 
with  its  level  surface,  is  more  like  some  vast  plateau. 
Now,  that  the  temperature  of  a  plateau  exceeds  that 


THE   SUN   DOMINANT 


99 


of  a  peak  at  the  same  height,  table-lands  on  the  earth 
make  evident.  Humboldt  cited  the  Himalaya.  On 
the  north  side  of  this  great  range,  both  snow-line  and 
timber-line  are  three  thousand  feet  higher  than  on  the 
south  side,  a  climatic  lift  brought  about  by  the 
Tibetan  table-lands  on  the  north;  and  this  in  spite 
of  the  contrary  effect  of  slope  exposure. 

But  we  may  get  instances  nearer  home.     In  scan- 
ning  Merriam's   chart    Lowell   was   struck   by  a  fact 


.After  a  plate  in  "  North  American  Fauna,  No.  3,"  U.  S.  Dept.  of  Agriculture,  Division  of 
Ornithology  and  Mammalogy,  by  Dr.  Merriam. 

DIAGRAMMATIC  PROFILE  OF  THE  SAN  FRANCISCO  AND  O'LEARY  PEAKS, 
FROM  SOUTHWEST  TO  NORTHEAST 

The  diagram  shows  the  several  life  zones  and  the  effects  of  slope  exposure,  but 
also  shows  what  is  unnoticed  by  the  monograph,  the  effect  of  a  plateau  upon 
life.  The  location  of  the  Lowell  Observatory  is  indicated  by  the  star. 

unmentioned    by    Merriam.     Superposed    upon    the 
more  evident  dip  of  the  zones  down  from  the  south- 


ioo      MARS   AS   THE  ABODE   OF   LIFE 


west  to  the  northeast  a  divergence  in  this  dip  may  be 
recognized,  the  dip  increasing  as  the  zones  mount.  It 
at  once  occurred  to  him  that  this  must  be  due  to  the 
mass  of  land  upon  which  each  rested.  That,  in  short, 
the  isoflors  rose  relatively  to  the  north  because  of  the 


SHOWING  EFFECT  OF  PLATEAU  ELEVATION  ON  TREE  ZONES  — 
LESS  ELEVATION 

higher  plateau  base  there.  To  test  this  he  made  a 
series  of  camping  trips  this  last  summer,  1907,  on 
and  about  the  peaks,  measuring,  with  an  aneroid 
checked  by  trigonometric  survey,  the  heights  at 
which  the  several  species  of  trees  grew  and  from  his 
data  laying  down  the  isoflors.  The  outcome  was  more 


THE   SUN   DOMINANT 


101 


striking  when  thus  carefully  done  than  it  had  been 
in  Merriam's  map,  and  quite  conclusive  as  to  cause. 
It  is  here  presented  to  the  reader  in  a  series  of  charts. 
In  these  charts  not  only  does  the  dip  decline  less 
the  nearer  the  tree  zone  stands  to  the  plateau,  but  in 


SHOWING  EFFECT  OF  PLATEAU  ELEVATION  ON  TREE  ZONES  — 
GREATER  ELEVATION 

the  nearest  of  all,  the  pine  zone,  the  influence  of  the 
northern  plateau  is  actually  sufficient  to  counteract 
the  opposite  effect  of  slope  exposure  and  cause  the 
isoflor  to  rise  toward  the  north. 

The  explanation  of  the  matter  is  not  far  to  seek. 


102      MARS   AS   THE  ABODE   OF   LIFE 


-AS/"//—'  -» 


\^ 


DIAGRAMS  OF  Two  CRATERS  SHOWING  GREATEST  COLD  N.N.W. 

Each  bit  of  plateau  helps  warm  its  neighbor,  and  so 
keeps  a  heat  that  else  had  radiated  away.  So  much 
for  the  effect  of  but  a  small  plateau.  If  even  a  lim- 


THE   SUN   DOMINANT  103 

ited  area  of  high  ground  can  so  far  ameliorate  the 
temperature,  how  much  more  would  be  accomplished 
were  it  to  become  world-wide  ? 

That  we  do  not  find  animal  and  vegetable  life  at 
the  tops  of  our  highest  mountains  is  due  to  other 
cause  than  elevation ;  namely,  to  the  restricted  nature 
of  the  habitat  upon  the  pointed  needle  of  a  peak,  sep- 
arated by  impassable  gulfs  from  other  equally  limited 
areas.  The  animal  has  no  range  of  forage  and  no 
chance  of  commerce  with  its  kind.  This  is  one  rea- 
son for  the  absence  of  life  upon  isolated  pinnacles. 
Yet  even  so  its  presence  proves  surprising.  On  the 
very  pinnacle  of  the  San  Francisco  peaks,  at  12,630  feet, 
the  tracks  of  a  chipmunk  showed  clearly  in  the  snow 
on  the  occasion  of  its  ascent  upon  October  15.  Another 
exterminating  cause  is  the  wind  that  of  necessity  always 
draws  over  a  peak  at  the  slightest  provocation.  The 
consequent  drain  upon  an  animai's  own  heat  when 
made  under  low  temperatures  is  fatal  to  life.  Man  can 
endure  70°  below  zero  F.  if  the  air  is  still,  but  perishes 
at  40°  below  under  the  least  wind.  Even  a  breeze,  there- 
fore, is  equivalent  to  a  fall  of  30°  F.  in  the  temperature. 

By  both  temperature  and  appearance,  then,  water-  water-vapor 
vapor  proves  a  constituent  of  the  Martian  atmosphere.  '-J^J' 
Now,  the  vapor  of  water  is  a  light  gas,  the  lightest  of 
the  constituents  of  our  own  air,  and,  in  consequence, 
by  the  laws  of  gases,  among  the  most  difficult  for  a 


io4      MARS   AS   THE   ABODE   OF   LIFE 

planet  to  retain.  Its  presence,  therefore,  in  a  planet's 
gaseous  envelope  is  of  the  nature  of  a  guarantee  that 
less  volatile  associates  are  also  to  be  found  there. 
These,  in  an  increasing  order  of  weight,  are  nitrogen, 
oxygen,  and  carbonic  acid  gas.  So  we  may  con- 
clude that  these  are  probably  also  to  be  found  on 
Mars. 

But  we  are  far  from  having  to  rely  upon  such  infer- 
ence, well  founded  in  principle  as  it  is,  for  our  knowl- 
edge of  the  existence  of  these  important  gases  in  the 
atmosphere  of  the  planet.  Modern  observation  of  a 
quite  unrelated  class  of  features  puts  their  presence 
there  upon  a  secure  footing  —  a  planting  on  the  prem- 
ises of  both  feet  instead  of  one  by  the  logical  body  of 
fact ;  and  that,  too,  by  reason  of  a  descent  from  the 
air  to  the  solid  surface  of  the  ground.  It  is  the  now 
recognized  constitution  of  one  of  the  two  great  classes 
of  markings  that  diversify  the  disk  which  has  given  us 
the  necessary  information.  The  blue-green  regions 
have  proved  themselves  the  sibyls  in  the  case. 

In  form  first,  in  color  subsequently,  the  blue-green 
areas  commended  themselves  as  seas  and  oceans  to  the 
mind  of  the  early  areographers.  Even  Schiaparelli  so 
considered  them.  Nor  at  that  stage  of  acquaintance 
was  the  characterization  at  all  far-fetched.  But  as 
these  seeming  seas  were  better  scanned,  differences  of 
tint  became  apparent  in  them.  This  should  have 


THE   SUN   DOMINANT  105 

shaken  belief  in  their  character,  but  so  tenacious  is 
an  idea  when  once  it  has  taken  root  that  the  dis- 
covery awoke  no  doubt.  The  oceans  were  merely 
spoken  of  as  shallower  in  some  places  than  in  others, 
as  if  thousands  of  square  miles  of  water  so  few  feet 
deep  that  the  bottom  showed  through  did  not  of  itself 
need  explanation. 

Next,  these  very  differences  showed  variation. 
Areas  as  large  as  Great  Britain,  and  often  very 
much  larger,  would  lighten  in  the  course  of  a  few 
weeks  in  a  perfectly  unmistakable  manner.  Indeed, 
the  greater  part  of  the  whole  southern  hemisphere  of 
the  planet  would  thus  doff  one  tone,  and  even  tint, 
to  don  another  at  surprisingly  short  notice,  and  this 
without  anything  approaching  a  correspondingly  sizable 
darkening  elsewhere. 

When  we  set  ourselves  to  consider  the  matter  in  the 
light  of  what  was  seen,  we  perceive  that  such  absence 
of  reciprocity  is  fatal  to  the  theory  of  a  liquid  film. 
For  were  the  transformation  some  subtle  shift  of  sub- 
stance, what  one  part  lost,  another  must  have  gained. 
Either  transferred  as  water  elsewhere  or  wafted  away, 
to  be  deposited  as  snow  about  the  pole,  the  thing 
should  still  be  somewhere  in  the  planet's  aqueous 
economy.  Yet  neither  of  these  counterbalancing  ef- 
fects was  perceptible.  As  water  it  had  vanished,  and 
the  polar  caps  were  not  increased. 


io6      MARS   AS   THE  ABODE   OF   LIFE 

Vegetation  Left,  thus,  without  3.  marine  character  to  their  name, 

we  are  led  to  inquire  what  these  patches,  which  both 
in  form  and  color  ape  water,  can  in  reality  be.  If  the 
great  blue-green  regions  be  observed  at  intervals  of  a 
few  weeks,  and  the  aspects  they  successively  present 
be  recorded  in  drawings,  intercomparison  suffices  to 
make  evident  that  the  metamorphoses  they  experience 
are  periodic,  and  the  period  that  of  the  planet's  year. 
The  changes,  then,  are  seasonal  in  cause.  That  is, 
they  depend  upon  the  sun.  And  in  proof  of  the 
relation,  their  fading  out  is  found  to  occur  in  winter, 
when  the  sun  is  least  operative,  and  their  greatest 
evidence  in  midsummer,  when  the  sun  is  locally  most 
potent. 

Now,  there  is  only  one  thing,  so  far  as  we  know, 
thus  obedient  to  the  sun  and  indicative  of  its  subser- 
viency by  a  change  of  hue  from  blue-green  to  ochre, 
and  that  is  vegetation.  Both  colors  are  self-accusa- 
tory. The  first  speaks  of  verdure  in  its  prime,  the 
second  of  the  change  of  the  leaf  to  the  sear  and  yellow 
stage,  just  as  it  takes  place  in  our  own  foliage  on  the 
approach  of  autumn's  frosts,  indicating  that  its  course 
is  run.  Not  otherwise  could  we  observe  it  from 
space,  should  we  mark  our  own  familiar  earth  change 
color  when  its  season's  work  was  done. 

Vegetation  thus  vouched  for,  the  constitution  of  the 
air  becomes  more  certain.  Besides  water-vapor,  oxy- 


THE   SUN   DOMINANT  107 

gen  and  carbonic  acid  gas  must  both  be  present,  and 
undoubtedly  nitrogen,  too,  since  in  the  matter  of 
density  it  holds  an  intermediate  position.  To  find 
that  the  Martian  air  is  made  up  of  our  old  familiar 
friends  in  the  matter  of  gas  is  an  important  step  to 
acquaintance  with  what  goes  on  upon  that  other  world. 
Though  we  are  indebted  for  our  knowledge  of  its 
existence  to  the  vegetation,  which  is  visible  while  the 
air  is  not,  it  is  in  fact  the  vegetation  that  is  indebted 
to  it  for  being  able  to  show  at  all. 

Of  organic  existence  there  the  main,  or  natural,  fea-  Mode  of 

-      i  1  >        r  11  i  r         manifestation 

tures  or  the  planets  race  could  not  be  looked  to  for  oflife> 
more  disclosure.  Indeed,  the  surprising  thing  is  that 
they  should  have  disclosed  so  much.  That  the  com- 
ing and  going  of  vegetation  should  be  visible  across 
the  thirty-five  million  miles  of  space  to  which  at  its 
least  the  gap  separating  us  from  Mars  is  reduced,  is 
little  short  of  marvellous.  As  for  a  direct  view  of  any 
animal  life  the  planet  might  support,  it  would  be  out 
of  the  question.  In  a  very  different  manner  would 
this  reveal  itself.  Not  through  its  body  should  we 
be  ware  of  it,  but  through  manifestation  of  its  mind. 
By  the  material  changes  in  the  surface  of  a  planet 
wrought  by  the  dominance  of  his  mind  over  matter 
would  the  other  world-worker  stand  confessed.  This 
we  shall  realize  if,  from  the  point  we  have  gained  in 
establishing  the  probable  existence  of  such  life,  we  go 


io8      MARS  AS   THE  ABODE   OF   LIFE 

on  to  consider  its  probable  character.  Such  can  be 
done  by  reviewing  the  experience  of  our  own  planet. 

From  what  has  taken  place  on  earth,  we  see  that 
cooling  and  complexity  of  organism  have  advanced  to- 
gether. Life  originated  here  as  soon  as  the  tempera- 
ture fell  below  the  boiling-point,  and  it  started  in 
water,  the  liquefying  of  which  out  of  steam  gave  it  at 
once  an  essential  factor  of  its  substance  and  an  environ- 
ment of  the  most  easily  satisfying  kind. 

An  upward  step  in  evolution  occurred  when  life 
stepped  out  upon  the  land.  While  less  directly 
favorable  to  life,  the  land  was  fraught  with  more  pos- 
sibilities for  organisms  capable  of  turning  them  to 
account.  Brain  was  needed,  and  brain  evolved. 

Brain,  indeed,  now  became  the  chief  concern  of 
nature.  The  character  of  the  habitat  undoubtedly 
brought  this  about  through  the  prizes  it  offered  the 
clever,  and  the  snuffing  out  to  which  it  consigned  the 
crass. 

For  long  the  animal  remained  thus  the  creature 
of  its  environment,  its  view  restricted  in  both  time 
and  space.  Greater  possibilities  came  in  with  man. 
Doubtless  his  was  no  very  dignified  entry,  though 
something  better  than  on  all  fours.  Brain  now  finally 
distanced  brawn,  and  even  in  his  savage  state  man 
became  a  being  that  others  feared.  From  thus  stand- 
ing primus  inter  pares,  he  soon  developed  into  first, 


THE   SUN   DOMINANT  109 

"  with  the  rest  nowhere."  Fire  and  clothes  raised  him 
to  some  independence  of  his  surroundings,  and  slowly 
he  began  to  take  possession  of  the  earth.  His  breech- 
ing, the  putting  on  by  the  race  of  the  toga  virilis,  was 
both  an  incident  of  his  rise  and  part  cause  of  it  as  well, 
for  it  made  him  superior  to  climate.  But  the  fertility 
of  brain,  however  humble  in  its  beginning,  which  sug- 
gested the  means  of  protecting  the  body,  devised  the 
methods  by  which  he  was  to  subjugate  the  earth. 

For  some  centuries  now  this  has  been  his  goal,  un- 
conscious or  confessed.  The  true  history  of  man  has 
consisted  not  in  his  squabbles  with  his  kind,  but  in  his 
steady  conquest  of  all  earth's  animals  except  himself. 
He  has  enslaved  all  that  he  could  ;  he  is  busy  in  ex- 
terminating the  rest.  From  this  he  has  gone  on  to 
turn  the  very  forces  of  nature  to  his  own  ends.  This 
task  is  recent  and  is  yet  in  its  infancy,  but  it  is  destined 
to  great  things.  As  brain  develops,  it  must  take  pos- 
session of  its  world. 

Subjugation  carries  its  telltale  in  its  train ;  for  it 
alters  the  face  of  its  habitat  to  its  own  ends.  Already 
man  has  begun  to  leave  his  mark  on  this  his  globe  in 
deforestation,  in  canalization,  in  communication.  So 
far  his  towns  and  his  tillage  are  more  partial  than  com- 
plete. But  the  time  is  coming  when  the  earth  will 
bear  his  imprint,  and  his  alone.  What  he  chooses, 
will  survive ;  what  he  pleases,  will  lapse,  and  the  land- 


i  io      MARS   AS   THE  ABODE   OF   LIFE 

scape   itself  become   the   carved    object  of  his   handi- 
work. 

Equally  applicable  is  this  deduction  to  planets  other 
than  the  earth.  Instead  of  its  being  true,  as  a  recent 
writer  remarked,  that  "  we  cannot  expect  to  see  any 
signs  of  the  works  of  inhabitants  of  Mars  if  such  ex- 
ist," precisely  the  opposite  is  the  case.  Until  the  ani- 
mal attain  to  dominance  of  his  world,  his  presence  on 
it  would  not  be  seen.  Too  small  in  body  himself  to 
show,  it  would  be  only  when  his  doings  had  stamped 
themselves  there  that  his  existence  could  with  certainty 
be  known.  Then  and  not  till  then  would  he  stand 
disclosed.  It  would  not  be  by  what  he  was,  but 
through  what  he  had  brought  about.  His  mind  would 
reveal  him  by  its  works  —  the  signs  left  upon  the 
world  he  had  fashioned  to  his  will.  And  this  is  what 
I  mean  by  saying  that  through  mind  and  mind  alone 
we  on  earth  should  first  be  cognizant  of  beings  on 
Mars. 


CHAPTER  IV 


MARS  AND  THE  FUTURE  OF  THE  EARTH 

STUDY    of   Mars   proves    that    planet   to   occupy 
earthwise  in  some  sort  the  post  of  prophet.     For, 
in    addition    to    the    side-lights    it    throws    upon    our 


COMPARATIVE  SIZES  OF  THE  EARTH  AND  MARS  WITH  THE  POLAR  CAPS 
OF  BOTH  IN  THEIR  SPRINGTIME. 

past,  it  is  by  way  of  foretelling  our  future.  It  enables 
us  to  no  mean  extent  to  foresee  what  eventually  will 
overtake  the  earth  in  process  of  time ;  inasmuch  as 
from  a  scrutiny  of  Mars  coming  events  cast  not  their 
shadows,  but  their  light,  before. 

It  is  the  planet's  size  that  fits  it  thus  for  the  role 
of  seer.  Its  smaller  bulk  has  caused  it  to  age  quicker 
than  our  earth,  and  in  consequence  it  has  long  since 


its  oceans. 


iiz      MARS   AS   THE  ABODE   OF   LIFE 

passed  through  that  stage  of  its  planetary  career  which 
the  earth  at  present  is  experiencing,  and  has  advanced 
to  a  further  one,  to  which  in  time  the  earth  itself  must 
come,  if  it  be  not  overwhelmed  beforehand  by  other 
catastrophe.  In  detail,  of  course,  no  two  planets  of 
different  initial  mass  repeat  each  other's  evolutionary 
history ;  but  in  a  general  way  they  severally  follow 
something  of  the  same  road. 

Mars  has  lost  It  is  in  the  matter  of  water  that  Mars  stands  forth 
as  a  prophet,  and  this  in  two  ways  :  as  polar  ice  and  as 
oceanic  expanses. 

The  first  of  these  has  reference  to  our  own  glacial 
epoch,  a  geologic  phenomenon  the  strangeness  and 
seeming  unaccountableness  of  which  has  grown  as 
scientists  have  contemplated  it  with  more  care.  That 
vast  areas  of  the  earth's  northern  hemisphere,  and  of 
the  southern,  too,  were  at  times  covered  by  a  continu- 
ous ice-sheet  is  a  fact  remarkable  enough  in  itself,  but 
grown  still  more  curious  from  the  difficulty  experi- 
enced in  assigning  it  adequate  cause.  Cosmic  cooling 
of  our  planet  will  not  explain  it,  certain  as  that  cooling 
is  ;  for  the  refrigeration  was  partial,  and  recurrent  as 
well.  Croll  tried  to  account  for  it,  but  ingenious  as 
his  idea  was,  it  will  not  hold  water  —  in  the  shape  of 
ice  —  in  the  form  in  which  he  put  it,  and  it  is  now 
virtually  abandoned  by  geologists,  although  it  contains 
considerable  truth. 


MARS  AND  FUTURE  OF  EARTH   113 

Now,  it  is  not  a  little  interesting  that  Mars  should 
have  something  to  say  upon  the  subject  —  something 
which  throws  light  upon  the  phenomenon  as  a  general 
planetary  process,  and  specifically  upon  its  occurrence 
on  our  earth.  It  is  because  Mars  happens  to  present 
precisely  the  astronomic  conditions  which  form  the 
basis  of  Croll's  theory,  and  at  the  same  time  shows 
the  exact  opposite  of  the  prescribed  results,  that  its 
evidence  is  valuable. 

The  relative  length  of  a  planet's  seasons  are  deter- 
mined by  the  elliptic  orbit  the  planet  pursues.  If  the 
axis  be  so  tilted  that  summer  of  one  hemisphere  occur 
when  the  planet  is  nearest  to  the  sun  and  therefore  also 
moving  swiftest,  that  summer  will  be  short  and  hot, 
while  the  corresponding  winter  will  be  long  and  cold. 
This  hemisphere  will  have  seasons  of  extremes ;  the 
other  reversely  will  have  long,  cool  summers  and 
short,  warm  winters  or  seasons  of  means.  The  greater 
the  eccentricity  of  the  orbit  the  greater  the  accentua- 
tion between  the  two  hemispheres. 

Glaciation  would  result  from  a  greater  deposition  of 
hoar-frost  or  snow  in  winter  than  the  succeeding 
summer's  sun  could  melt.  A  lengthening  of  winter 
at  the  expense  of  summer  would  seem,  therefore,  able 
to  bring  it  about.  Now,  a  greater  eccentricity  in  the 
orbit  of  the  earth  than  is  the  case  to-day  existed  in  the 
past,  and  would  produce  just  this  effect.  So  Croll 


ii4      MARS   AS   THE   ABODE   OF   LIFE 

argued  that  it  had  done  so.  Unfortunately  for  the 
theory,  Mars  moves  now  in  an  orbit  more  eccentric 
than  that  of  the  earth  ever  can  have  been,  and  the 
nearest  approach  of  the  planet  to  the  sun  occurs,  too, 
not  far  from  the  summer  solstice  of  its  southern  hemi- 
sphere, yet  that  hemisphere  which  should  show  gla- 
ciation  not  only  does  not,  but  comes  farther  from 
doing  so  than  the  other.  For  while  the  northern  cap 
diminishes  from  78°  across  to  6°,  the  southern 
dwindles  from  96°  to  nothing.  This  shows  that 
while  for  various  reasons  the  longer  winter  results  in 
a  greater  deposition,  the  shorter  but  hotter  summer 
of  its  hemisphere  more  than  melts  it  away. 

Now,  if  we  increase  pro  rata  the  precipitation  over 
the  whole  planet,  we  perceive  that  the  extent  of  the 
southern  cap  at  its  greatest  will  still  more  outdo  the 
northern  one,  and  as  the  melting  capacities  of  the  two 
summers  are  approximately  constant  quantities,  a  time 
will  come  when  the  remains  of  the  southern  cap  will 
surpass  that  of  the  other,  and  glaciation  ensue.14 

Such  passing  by  one  cap  of  the  other  in  the  race 
toward  glaciation  is  bound  to  occur,  whatever  the  eccen- 
tricity, if  it  be  anything  at  all,  provided  the  precipitation 
be  sufficient.  On  the  other  hand,  not  only  no  glaci- 
ation can  result  unless  the  precipitation  exceed  a  certain 
quantity,  but  in  want  of  it  the  ice-cap  is  actually  less 
in  the  hemisphere  where  we  should  expect  it,  that  of 


MARS  AND  FUTURE  OF  EARTH   115 


extremes,  than  in  the  other.  Whatever  the  cause  of 
increased  snowfall,  the  effect  is  the  same.  It  is,  then, 
the  amount  of  precipitation,  however  it  be  brought 
about,  and  not  increase  of  eccentricity,  essential  as 
eccentricity  is,  which  is  the  determining  cause  of  an 
ice  age. 

To  perish  by  wholesale  glaciation  is  not  therefore 
the  inevitable  doom  of  a  planet.  Unless  water  be  in 
abundance,  secular  cooling  will  not  necessarily  bring  it 
about,  and  Mars  shows  us 
that  a  planet  may  wholly 
escape  such  a  termination 
to  its  career  by  having  pre- 
viously parted  with  suffi- 
cient moisture,  and  actually 
enjoy  an  anti-glacial  state 
in  its  old  age. 

The  thought  leads  us  to 
the  second  matter  in  which 
the  present  state  of  Mars 
foretells  the  future  of  the 
earth.  Not  only  does  unhampered  age  15  preclude  the 
possibility  of  a  death  by  frost ;  it  tends  to  a  death  by 
thirst  by  deprivation  of  water.  As  we  saw  when 
reasoning  upon  the  blue-green  areas,  Mars  apparently 
had  seas  in  the  past,  though  it  possesses  none  to-day. 
To  the  student  of  the  planet  the  question  at  once 


LINES  IN  THE  DARK  AREAS  OF 
MARS,  SHOWING  THAT  THE 
LATTER  ARE  NOT  SEAS. 

From  a  drawing  made  July  n,  1907. 


ii6      MARS   AS   THE   ABODE   OF   LIFE 

arises,  how  this  not  wholly  regrettable  deprivation  was 
acquired,  since  it  was  not  congenital. 

There  are  two  ways  in  which  a  planet  not  only  may, 
but  inevitably  must,  be  robbed  of  its  water  supply  — 
from  without  and  from  within.  It  may  lose  its  oceans 


November  5,  1907,  September  i,  1907. 

PARING   ON   THE  TERMINATOR   (RIGHT-HAND    EDGE)    OF    MARS    WHERE 
DARK  AREAS  CROSS  ;    INDICATING  THAT  THEY  LIE  AT  A  LOWER  LEVEL 

THAN  THE   REST  OF  THE   SURFACE,   AND   WERE  ONCE   SEAS. 

by  absorption  into  its  interior  and  by  a  slow  depletion 
into  space.  While  a  body  is  yet  molten,  the  conti- 
nuity of  its  substance  bars  entrance  to  aught  else  ;  but 
as  it  cools  and  shrinks,  fissures  and  crevices  open  in  it, 
and  into  these  the  surface  water  sooner  or  later  finds 
its  way.  As  a  planet  ages,  its  very  wrinkles  must 
cause  it  to  dry  up.  This  is  one  drain  upon  its  surface 
seas  that  is  sure  to  occur.  The  other  is  equally  sched- 
uled to  happen.  It  depends  upon  the  fact  that  gases 
are  composed  of  particles  called  molecules  travelling  at 
great  speeds.  Temperature  is  the  expression  of 


MARS   AND   FUTURE   OF   EARTH      117 

this  energy,  varying,  indeed,  as  the  product  of  the 
square  of  the  speed  by  the  mass  of  the  particle.  Such 
motion  it  is  that  causes  gases  to  expand.  In  their 
journeyings  the  molecules  collide,  and  thus  give  and 
take  velocity.  In  consequence,  some  are  moving 
swiftly,  some  slowly.  The  molecules  are  flying  about 
in  all  directions,  and  as  long  as  they  do  not  go  too  fast, 
the  planet  about  which  they  act  as  atmosphere  con- 
tinues to  control  them  by  its  gravity.  This  it  can 
continue  to  do  up  to  a  speed  called  its  critical  velocity, 
which  is  the  velocity  the  planet  can  impart  to  a  particle 
falling  freely  to  it  from  infinite  space.  For  the  planet 
can  annul  just  the  speed  it  is  able  to  cause  and  no 
more.  But  if,  in  their  give  and  take  of  motion,  a 
molecule  gets  to  going  faster  than  the  critical  velocity, 
it  will  escape  into  space  and  start  on  interstellar 
travels  of  its  own.  These  molecules  will  never  return 
to  the  body  they  have  left,  and  as  such  desertion  is 
constantly  going  on,  it  will  eventually  deplete  the 
planet  of  all  the  gases  it  once  possessed. 

Now,  from  any  liquid  surface  evaporation  is  perpet- 
ually taking  place ;  so  that  an  ocean  is  being  slowly 
and  silently  lifted  into  the  air.  Ordinarily  its  particles 
fall  again  in  the  shape  of  rain,  but  not  those  which  by 
collision  gain  sufficient  speed.  These  from  their  tip- 
toe vantage-point  take  final  flight  into  interplanetary 
space.  The  smaller  the  body,  the  sooner  must  it  lose 


u8      MARS   AS   THE   ABODE   OF   LIFE 

its  seas,  for  the  less  can  it  hold  on  by  its  lesser  gravity 
to  its  water-vapor.  Three  stages  in  the  inevitable 
parting  with  its  hydrosphere  are  exemplified  to-day 
by  the  earth,  Mars,  and  the  moon.  On  the  earth 
the  sea-bottoms  still  hold  seas,  on  Mars  they  only 
nourish  vegetation,  on  the  moon  they  contain  noth- 
ing at  all. 

Parity  of  reasoning  points  to  the  road  the  earth 
must  follow.  Sharpened  by  science,  we  actually  per- 
ceive the  progress  along  it  that  our  world  has  already 
made. 

The  oceans  of  Attention  shows  that  loss  of  water  has  been  going 
on  tnrough  tne  eons  tnat  have  passed,  and  that  the 
process  is  taking  place  under  our  very  eyes  to-day. 
Once  laid  down,  the  earth's  oceans  have  been  slowly 
disappearing  since.  The  reason  they  have  not  wholly 
departed  is  partly  because  there  was  so  much  to  go, 
partly  because  its  greater  mass  has  helped  the  earth  to 
hold  on  to  them  the  better.  The  speed  of  departure 
the  earth  can  restrain  is  more  than  double  that  for 
Mars  —  6.9  miles  per  second  instead  of  3.1  miles. 
Thus  the  way  by  the  skies  is  less  available.  On  the 
other  hand,  the  greater  initial  heat  of  its  interior  has 
kept  the  water  from  sinking  in  to  a  degree  beyond 
what  is  possible  in  a  smaller  globe.  The  earth  has 
thus  lagged  in  its  losings,  but  it  has  lost,  for  all 
that. 


MARS  AND  FUTURE  OF  EARTH   119 

Withdrawal  of  water  should  show  in  a  diminution  Gain  of  land 
of  the  surface  of  the  planet  covered  by  the  sea.     Ob-  ™ 
servation  proves  this  to  be  a  fact.     With  research  we  Europe, 
may  assure  ourselves  that  the  depletion  is  in  process. 


From  Dana's  "  Manual  of  Geology."     (American  Book  Company.)] 

MAP  OF  NORTH  AMERICA,  SHOWING  APPROXIMATELY  THE  AREAS  OF  DRY 
LAND  (INDICATED  BY  THE  WHITE  SPACES)  AT  THE  CLOSE  OF  ARCHAEAN 
TIME. 

The  late  Professor  Dana  of  New  Haven  constructed 
maps  of  North  America  from  the  evidence  afforded 
by  the  geologic  sedimentary  strata,  showing  what  of  it 
had  been  terra  firma  in  the  successive  periods  of 


120      MARS   AS   THE   ABODE   OF   LIFE 

geologic  time.  A  comparison  of  his  charts  gives 
most  interesting  and  conclusive  proof  that  the  land 
in  North  America  has  been  gaining  at  the  expense  of 
the  sea  from  the  time  the  sea  first  was.* 

But  North  America  was  not  alone  in  its  natural 
territorial  aggrandizement.  Europe  exemplifies  the 
same  generally  steady,  if  temporarily  fluctuating,  con- 
quest of  terrain.  As  in  North  America,  the  land 
started  at  the  north,  and  encroached  upon  the  ocean 
farther  and  farther  southward.  What  we  commonly 
regard  as  Europe  was,  in  paleozoic  times,  under  the 
surface  of  the  sea.  Only  the  north  of  Scotland  and 
Scandinavia  protruded.  Had  the  present  great  navies 
of  the  world  been  in  existence  then,  they  would  have 
found  ample  scope  for  their  operations,  but  would 
have  missed  their  present  bases  of  supply,  since  they 
could  have  sailed  over  the  sites  of  London,  Paris,  or 
Berlin. 

Wherever  geologists  have  studied  them,  the  strata 
tell  the  same  tale.  The  land  has  spread,  the  ocean 
shrunk  from  the  time  they  first  partitioned  out  the 
surface.  Now,  a  general  universal  gain  of  the  sort  can 
mean  only  one  of  two  things.  Either  the  oceans  have 
been  deepening  or  disappearing.  If  crumplings  of 
the  crust  have  caused  increased  depression  in  the 
ocean  basins,  they  should  have  been  equally  busied  in 

*See  "  Mars  and  its  Canals."     Macnrillan. 


MARS  AND  FUTURE  OF  EARTH   121 

elevating  the  continental  plateaux.  There  is  no  evi- 
dence of  any  widespread  raisings  of  the  sort.  For 
though  mountain-chains  have  been  pushed  up,  they 
are  effects  of  local  crumpling,  not  of  broad  buckler- 
like  embossment."  From  the  very  fact  that  they  are 
fractures,  they  relegate  long,  low  uplifts  to  the  past. 
We  are  left,  then,  with  the  alternative  that  the  seas 
have  been  slowly  reduced  in  volume. 

Testimony  to  this  same  effect  keeps  cropping  up.  Lowering  of 
Only  the  other  day  the  Chagos  Archipelago,  a  little-  thesea-level 
known  congeries  of  coral  reefs  south  of  the  Maldives, 
was  studied  by  Mr.  Stanley  Gardiner,  of  the  Sladen 
Expedition,  who  concluded,  from  the  appearance  of 
the  atolls,  which,  like  oases  in  the  desert,  dot  the 
waste  of  waters,  that  an  alteration  of  level  has  been 
universal  throughout  the  Indo-Pacific  coral-reef  re- 
gion, from  latitude  30°  N.  to  latitude  25°  S.  From 
the  fact  that  it  was  so  widespread,  there  being  evi- 
dence of  many  local  upheavals  throughout  the  zone, 
he  inferred  it  to  be  due  to  a  withdrawal  of  water  rather 
than  to  a  change  of  level  in  the  ocean  floor.  The 
amount  required  to  account  for  the  appearance  varied 
from  five  to  thirty-five  feet.  Thirty-five  feet  may  at 
first  sound  small,  but  occurring  over  hundreds  of 
thousands  of  square  miles,  it  means  a  good  deal  of 
water  lost. 

What  is  exhaling  in  the  oceanic  areas  may  be  gauged  inland  seas. 


122      MARS   AS   THE  ABODE   OF   LIFE 

by  what  is  transpiring  in  the  smaller  cut-off  bodies 
of  water,  such  as  the  Caspian,  the  Sea  of  Aral, 
and  the  Great  Salt  Lake.  For  the  drainage  basins  of 
these  inland  seas  are  not  only  comparable  with,  but 
actually  larger  in  proportion  than,  those  of  the  oceans. 
Consequently  they  are  fed  the  better  of  the  two. 
Nevertheless,  they  are  all  with  one  consent  evaporat- 
ing at  a  very  perceptible  rate.  Most  of  them  are 
below  the  level  of  the  sea,  which  in  itself  speaks  for 
the  depletion  undergone  since  they  were  left  behind 
by  the  retreating  main  body  of  water.  Marine  shells, 
fishes,  and  seals,  persisting  in  the  Caspian  still,  testify 
to  its  abandoned  character.  Seals,  indeed,  witness  to 
its  now  distancing  its  greater  prototype  in  its  haste 
to  be  gone,  in  spite  of  the  huge  fresh-water  drainage 
it  at  present  receives.  For  in  the  great  Kara  Bugas 
Gulf,  on  the  Caspian's  eastern  side,  the  evaporation 
is  so  rapid  that  while  a  current  sets  into  it  from  its 
narrow  opening,  with  no  compensating  outward  one, 
it  is  becoming  so  salt  that  seals  can  no  longer  live 
there.  The  Caspian  is  disappearing  before  our  eyes, 
as  the  remains,  some  distance  from  its  edge,  of  what 
once  were  ports  mutely  inform  us.*  Even  so  is  it 
with  the  Great  Salt  Lake,  the  very  rate  of  its  sub- 
sidence being  known  and  measured. 

The  earth,  then,  is  going  the  way  of  Mars.      As 

*  See  Huntington,  recent  examination  of  the  shores  of  the  Caspian. 


MARS   AND   FUTURE   OF   EARTH      123 

there  now,  so  here  in  time  will  be  ushered  in  a  phase 

raqueousness. 


of  planetary   evolution   to  which  the  earth  as  yet  is 


stranger  —  the  purely  terrestrial,  as  opposed  to  the 
present  terraqueous,  character  of  its  surface.  Much 
must  surely  follow  such  a  change  of  scene.  What 
it  will  be  like  we  must  study  Mars  to  know,  since 
Mars  presents  us  the  picture  of  a  world  that  has 
reached  that  pass.  To  all  of  us  this  cannot  but 
offer  a  certain  exploratory  incentive  —  one  concerned 
not  with  space  alone,  but  with  time.  For  while  we 
directly  scan  the  planet  for  what  it  has  to  say  about 
itself,  we  are  indirectly  reading  a  story  which  has  some- 
thing to  tell  of  our  own  future  career.  If  we  can 
succeed  in  separating  in  this  the  particular  from  the 
generic,  what  is  local  to  Mars  from  what  is  cosmic  in 
character,  we  shall  do  on  a  broad  scale  what  the  early 
astrologers  thought  to  do  on  a  narrow  one,  and  in- 
stead of  reading  in  the  skies  the  fortunes  of  individuals, 
decipher  there  the  fate  of  the  whole  earth. 

Something  further  of  this  sort  we  may  indeed  do, 
and  this  by  help  of  the  same  principle  that  led  us  to 
the  loss  of  seas.  The  drying  up  which  causes  their 
extinction  is  no  less  active  on  the  land.  Being  a 
general  deprivation  common  to  the  whole  planet,  the 
two  kinds  of  surface  must  suffer  synchronously.  The 
effects,  however,  are  much  less  bearable  on  terra  firma. 
What  in  the  withdrawal  of  water  lowers  oceans  to 


124      MARS   AS   THE  ABODE   OF   LIFE 

affluence,  reduces  tracts  of  vegetation  to  penury.  The 
once  fertile  fields  become  deserts. 

Deserts.  Deserts  already  exist   on   the  earth,  and  the  name- 

less horror  that  attaches  to  the  word  in  the  thoughts 
of  all  who  have  had  experience  of  them,  or  are  gifted 
with  imagination  to  conceive,  is  in  truth  greater  than 
we  commonly  suppose.  For  the  cosmic  circumstance 
about  them  which  is  most  terrible  is  not  that  deserts 
are,  but  that  deserts  have  begun  to  be.  Not  as  local, 
evitable  evils  only  are  they  to  be  pictured,  but  as  the 
general  unescapable  death-grip  on  our  world.  They 
mark  the  beginning  of  the  end.  For  these  deserts  are 
growing.  First  steps  they  are  in  the  long  retreat  of 
water.  What  depauperates  the  forests  to  grass-lands, 
and  thence  to  wastes,  must  in  turn  attack  the  sea- 
bottoms  when  they  shall  have  parted  with  their  seas. 
Last  of  the  fertile  spots  upon  the  planet  because  of  the 
salts  the  streams  have  for  ages  washed  down,  and  of 
the  remnant  of  moisture  that  would  still  drain  into 
them,  eventually  they  must  share  the  fortune  of  their 
predecessors,  and  the  planet  roll  a  parched  orb  through 
space.  The  picture  is  forbidding ;  but  the  fact  seems 
one  to  which  we  are  constructively  pledged  and  into 
which  we  are  in  some  sort  already  adventured. 

Girdling  the  earth  with  what  it  takes  but  little 
personification  to  liken  to  the  life-extinguishing  ser- 
pent's coils,  run  two  desert-belts  of  country.  The 


MARS  AND  FUTURE  OF  EARTH   125 

one  follows,  roughly  speaking,  the  Tropic  of  Cancer, 
extending  northward  from  it;  the  other,  the  Tropic  of 
Capricorn.  Arizona  is  in  the  northern  band,  as  are 
the  Sahara,  Arabia,  and  the  deserts  of  central  Asia. 

Now,  these  desert-belts  are  widening.     In  the  great 
desert  of  northern  Arizona  the  traveller,  threading  his 

•* 


PETRIFIED  FOREST  OF  ARIZONA. 


way  across  a  sage-brush  and  cacti  plain  shut  in  by  ab- 
rupt-sided shelves  of  land  rising  here  and  there  some 
hundreds  of  feet  higher,  suddenly  comes  upon  a 
petrified  forest.  Trunks  of  trees  in  all  stages  of 
fracture  strew  the  ground  over  a  space  some  miles 
in  extent.  So  perfect  are  their  forms,  he  is  almost 
minded  to  think  the  usual  wasteful  wood-chopper  has 
been  by  and  left  the  scattered  products  of  his  art  in 
littered  confusion  upon  the  scene  of  his  exploit.  Only 
their  beautiful  color  conveys  a  sense  of  strangeness  to 


The  petrified 
forest  of 
Arizona. 


126      MARS   AS   THE  ABODE   OF   LIFE 

the  eye,  and  leaning  down  and  touching  them,  he  finds 
that  they  are  —  stone.  Chalcedony,  not  carbon! 
Form  has  outlived  substance  and  kept  the  resemblance, 
while  the  particles  of  the  original  matter  have  all  been 
spirited  away.  Yet  so  perfect  is  the  presentment,  one 
can  hardly  believe  the  fact,  and  where  one  fallen  giant 


ANOTHER  VIEW  OF  THE  PETRIFIED  FOREST  OF  ARIZONA. 

spans  a  barren  canon,  one  almost  thinks  to  hear  the 
sound  of  water  rushing  down  the  creek. 

But  it  is  some  millions  of  years  and  more  since  this 
catastrophe  befell,  and  the  torrent,  uprooting  it,  left  it 
prone,  with  limbs  outstretched  in  futile  grasp  upon 
the  other  side.  A  conifer  it  was,  cousin  only  to  such 
as  grow  to-day,  and  flourished  probably  in  the  Creta- 
ceous era ;  for  the  land  has  not  been  under  water  here 
since  the  advent  of  Tertiary  times. 


MARS  AND  FUTURE  OF  EARTH   127 

Nowhere  near  it,  except  for  the  rare  cottonwoods 
along  the  bank  of  the  Little  Colorado,  grows  anything 
to-day.  The  land  which  once  supported  these  forests  is 
incompetent  to  do  so  now.  Yet  nothing  has  changed 
there  since,  except  the  decreasing  water-supply.  Dur- 
ing Tertiary  and  Quaternary  time  the  rainfall  has 
been  growing  less  and  less.  Proof  of  this  is  offered 
by  the  great  pine  oasis  that  caps  the  plateau  of  which 
these  petrified  forests  form  a  part,  and  is  kernelled  by 
the  San  Francisco  peaks.  The  height  above  sea-level 
of  the  spot  where  the  chalcedony  trunks  are  strewn  is 
about  4500  feet ;  the  lower  present  limit  of  the  pine 
in  its  full  development  is  6500  feet.  Two  thousand 
feet  upward  the  verdure-line  has  retreated  since  the 
former  forests  were.  And  this  is  no  local  alteration, 
for  upon  the  other  side  of  the  plateau  petrified  remains 
of  trees  are  similarly  found. 

The  line  of  perpetual  green  has  risen  because  in 
desert  regions  the  moisture  is  found  most  plentiful 
nearest  to  the  clouds  from  which  it  falls  upon  a  parch- 
ing earth.  Streams,  instead  of  gathering  volume  as 
they  go,  are  largest  near  their  source,  and  grow  less 
and  less  with  each  fresh  mile  of  flow.  The  brooks 
descending  from  the  Anti-Lebanon,  in  Syria,  water 
the  gardens  of  Damascus,  and,  thence  issuing  upon 
the  plain,  lose  themselves  just  beyond  the  threshold  of 
its  gates.  So  in  the  Arizona  desert,  though  in  a  less 


i28      MARS   AS   THE   ABODE   OF   LIFE 

degree  ;  and  those  who  live  there  know  it  but  too  well. 
It  is  desert  craft  for  Indians  or  cow-boys  to  seek  water 
on  the  mesas,  not  at  their  base.  To  ascend  after  it  is 
one  of  the  footnotes  of  their  trade. 

Egypt  and  The  evidence  here  brought  before  us  of  a  secular 

parching  of  the  land  is  not  wholly  confined  to  western 
North  America.  Crossing  to  the  other  side  of  the 
world,  we  come  upon  like  remains.  Upon  the  plateau 
above  the  Nile,  near  Cairo,  the  traveller  goes  to  see 
another  petrified  graveyard  of  trees.  It  is  prehistoric, 
yet  contemporaneous  with  man  ;  for  paleolithic  and 
neolithic  implements  have  been  found  not  far  away, 

^.,.  showing  that  in  the  morning  of  his  race  man  lived  and 

hunted  in  these  forests,  where  neither  hunter  nor 
hunted  could  exist  to-day. 

Upon  the  southern  coast  of  the  Mediterranean,  at 
the  edges  of  the  great  Sahara,  are  to  be  seen  to-day 
the  ruins  of  vast  aqueducts  stalking  silently  across  the 
plains.  Fallen  into  decay  now,  they  attest  something 
more  than  the  passing  of  the  force  of  those  who  built 
them  from  the  scene  they  once  made  great.  Carthage 
has  crumbled  again  to  earth,  and  these  sentinelling 
arches  alone  remain  to  show  what  tentacles  of  suste- 
nance it  formerly  thrust  out.  Still  architecturally  im- 
pressive, they  span  not  space  alone,  but  time.  They 
testify  to  something  to  be  carried  as  well  as  to  a  city 
to  which  to  carry  it.  This,  now,  has  disappeared 


MARS  AND  FUTURE  OF  EARTH   129 

as  completely  as  its  drinkers.  At  the  present  day  the 
streams  are  incompetent  to  supply  the  aqueducts,  the 
very  presence  of  which  attests  that  in  the  past  this  was 
not  so.  The  land  has  parched  since  times  so  recent 
as  to  be  historic,  recorded  by  the  monuments  of  man. 

Nor  are  we  left  to  monuments  for  sole  light  upon 
the  subject.  The  very  fauna  has  changed.  Animals 
that  once  inhabited  the  land  are  unable  to  live  there 
now  because  of  the  increasing  aridity  of  the  habitat. 
Thus  they  add  their  testimony  to  that  of  the  mute 
purveyors  of  water  whose  occupation  is  gone.  The 
surprising  thing  is  that  it  should  all  have  happened  so 
recently.  In  a  startling  manner  it  brings  before  us  the 
speed  with  which  the  desert  is  gaining  on  the  habitable 
earth. 

Palestine  tells  the  same  story.  The  land  which  Palestine. 
once  flowed  with  milk  and  honey  can  hardly  flow  bad 
water  now.  Nor  is  this  because  the  folk  who  made 
its  greatness  have  since  been  scattered  over  the  face  of 
the  earth.  Much  goes  to  ruin  when  the  master  hand 
is  stilled,  but  no  rich  country  ever  lapsed  to  desert  for 
this  cause  unless  its  fertility  was  irrigation-made.  Con- 
clusive and  convincing  is  here  the  evidence  that  the 
land  itself  has  changed. 

Upon  comparing  the  places  where  this  desertism  Subtropical 
appears,  it  will  be  found  that  all  occur  in  a  band  about  ^'^j0  " 
the  earth  not  far  from  either  tropic,  and  extending 


130      MARS   AS   THE  ABODE   OF   LIFE 

north  or  south  from  it  according  to  the  hemisphere 
concerned.  Now,  when  we  turn  to  the  tables  of  the 
rainfall  for  different  parallels,  we  find  this  localization 
explained. 

It  is  precisely  in  these  belts  that  the  average  rainfall 
is  least,  except,  indeed,  far  north,  where  the  steppes 
attest  to  like  aridity.  The  occurrence  of  the  deserts 
is  thus  an  affair  of  the  circulation  of  the  atmosphere, 
and  from  that  fact  is  lifted  at  once  into  the  region  of 
general  planetary  evolution.  For  atmospheric  circula- 
tion is  a  necessary  consequence  of  a  body  having  an 
atmosphere  and  being  exposed  to  the  action  of  the 
sun.  The  general  effects  of  it  are  as  follows :  The 
equatorial  region,  being  the  most  continuously  heated 
by  the  solar  beams,  the  air  above  it  rises  and  flows 
over  at  the  top,  necessarily  poleward.  The  air  about 
the  tropics  flows  in  to  take  its  place.  Meanwhile  the 
lower  portion  of  the  equatorial  emigrant,  finding  the 
space  below  less  occupied,  descends  to  earth  in  the 
forties,  causing  the  prevailing  winds  in  those  regions. 
The  upper  part  proceeds  more  or  less  spirally  round 
the  pole.  This  general  circulation  is  independent  in 
its  main  action  of  the  character  of  the  ground.  Areas 
of  sea  and  land  modify  the  motions,  but  do  not  nega- 
tive the  results. 

Now,  keeping  this  circulation  in  the  mind's  eye,  we 
note  that,  other  things  equal,  those  winds  that  descend 


MARS  AND  FUTURE  OF  EARTH   131 

from  colder  regions  to  warmer  ones  must  be  dry. 
For,  on  being  heated,  air  becomes  capable  of  taking 
up  more  moisture  than  before,  and  is  by  this  re- 
strained from  depositing  the  water  it  already  contains 
in  the  form  of  rain  or  snow  or  dew.  It  thus  keeps 
with  it  such  moisture  as  it  has  or  as  it  acquires,  and 
instead  of  being  a  bountiful  dropper  of  fatness  from 
its  clouds,  courses  over  the  surface  a  scorching  sirocco. 
Such  is  the  fundamental,  uncomplicated  process,  and, 
in  consequence,  desert-belts  are  bound  to  form  in  time, 
and  just  where  we  find  those  of  the  earth  to-day,  bar- 
ring exceptions  locally  explained.  For  adventitious 
bodies  of  water  over  which  these  winds  pass  may  sup- 
ply them  with  water  which  mountain-chains  may  pre- 
cipitate again  on  their  windward  side  by  the  cooling  of 
the  winds  due  to  rising  up  their  flanks.  Either  of 
these  accidents  of  surface  may  thus  modify  the  effect 
without  affecting  the  principle. 

Turning  now  to  Mars,  we  find  what  is  but  in  its  Planetary 
infancy  on  earth,  there  in  full  control.     Not  only  are  ^"^ed 
the  desert-belts  in    existence,  but  the  whole   surface,  Man. 
except  for  the  sea-bottoms,  has  gone  the  same  way. 
Five-eighths  of  it  all  is  now  an  arid  waste,  unrelieved 
from  sterility  by  surface  moisture  or  covering  of  cloud. 
Bare  itself,  it  is  pitilessly  held  up  to  a  brazen  sun,  un- 
protected by  any  shield  of  shade.   •' 

That   such    is    the    case  with  our  neighbor  certain 


132      MARS   AS   THE  ABODE   OF   LIFE 

points  about  it  indicate.  The  first  of  these  is  hue. 
The  fiery  color  from  which  Mars  was  named  turns  out 
in  the  telescope  to  be  an  ochre  dashed  with  red.  This 
is  just  the  tint  our  own  deserts  show  when  one  looks 
down  on  them  from  a  mountain  peak.  The  next 
thing  is  their  unalterableness.  Except  for  seeming 
ruddier  at  times,  they  change  not,  the  seasons  that  so 
transform  the  blue-green  areas  passing  over  them  in 
vain.  Thus  both  in  look  and  deed  they  bespeak 
themselves  vast  Saharas,  these  great  ochre  stretches  of 
the  disk. 

Their  positioning  tells  the  same  story.  This  we 
perceive  on  considering  what  their  situation  is  as  com- 
pared with  what  it  should  be  for  such  state. 

Absence  of  moisture  should  not  alter  the  general 
wind  circulation  sketched  above,  and  we  should  expect 
to  find,  whatever  the  planet,  the  wet  and  dry  zones 
much  what  they  are  on  the  earth,  if  trace  of  them  still 
existed.  To  the  map  of  Mars  we  therefore  turn  to 
mark  whether  this  be  so.  In  such  envisagement,  one 
antedating  circumstance  must  be  allowed  for :  the  local 
positioning  of  the  oceanic  basins ;  for  an  ocean,  by 
reason  of  its  original  supply,  would  outlast  its  latitu- 
dinal time-limit.  Its  marine  constitution  would  defy 
the  law. 

Now,  the  oceans  of  Mars  lay  in  the  southern  hemi- 
sphere of  the  planet.  This  qualifies  the  action  in  that 


MARS  AND  FUTURE  OF  EARTH   133 

hemisphere,  and  makes  the  southern  subtropic  zone 
one  of  verdure  to-day.  This,  therefore,  is  no  dis- 
proof of  the  general  law ;  it  is  but  an  added  argument 
that  these  present  blue-green  areas  were  seas  at  some 
former  epoch. 

Otherwise  is  it  with  the  surfaceography  of  the 
northern  hemisphere,  since  in  the  beginning  that  was 
probably  fairly  free  from  land-and-water  distribution 
of  a  sufficiently  pronounced  type  to  hinder  the  play  of 
the  desert-making  tendency.  Here,  then,  we  should 
look  for  confirmation  of  the  principle  that  the  sub- 
tropic  zone  should  be  more  arid  than  the  temperate 
one,  and  here  we  find  something  which  is  suggestive. 
The  southern  subtropic  zone  is  destitute  of  blue-green 
areas  —  that  is,  areas  of  vegetation  —  all  round  the 
planet.  Not  so  the  temperate  zone  above  it.  In  the 
latter  are  found  all  the  larger  blue-green  regions  in  the 
planet's  northern  hemisphere  —  the  Mare  Acidalium, 
the  Propontis,  and  the  Wedge  of  Casius.  And  all 
these  are  approximately  upon  the  same  parallel  of  lati- 
tude. The  Lucus  Niliacus,  and  the  Mare  Acidalium 
stretch  from  latitude  29°  N.  to  latitude  55°;  the  Pro- 
pontis from  37°  to  48° ;  and  the  Wedge  of  Casius 
from  35°  to  56°.  That  such  consensus  in  situation  can 
be  due  to  chance  is  certainly  unlikely.  Here,  then, 
linger  the  last  vestiges  of  vegetation  of  the  northern 
hemisphere. 


134      MARS   AS   THE  ABODE   OF   LIFE 

The  opaline  As  important  is  the  present  great  extent  of  the 
Martian  deserts.  Beautiful  as  the  opaline  tints  of  the 
planet  look,  down  the  far  vista  of  the  telescope-tube, 
they  represent  a  really  terrible  reality.  To  the  bodily 
eye,  the  aspect  of  the  disk  is  lovely  beyond  compare ; 
but  to  the  mind's  eye,  its  import  is  horrible.  That 
rose-ochre  enchantment  is  but  a  mind  mirage.  A  vast 
expanse  of  arid  ground,  world-wide  in  its  extent, 
girdling  the  planet  completely  in  circumference,  and 
stretching  in  places  almost  from  pole  to  pole,  is  what 
those  opaline  glamours  signify.  All  deserts,  seen  from 
a  safe  distance,  have  something  of  this  charm  of  tint. 
Their  bare  rock  gives  them  color,  from  yellow  marl 
through  ruddy  sandstone  to  blue  slate.  And  color 
shows  across  space  for  the  massing  due  to  great  extent. 
But  this  very  color,  unchanging  in  its  hue,  means  the 
extinction  of  life.  Pitilessly  persistent,  the  opal  here 
bears  out  its  attributed  sinister  intent. 

To  let  one's  thoughts  dwell  on  these  Martian  Saharas 
is  gradually  to  enter  into  the  spirit  of  the  spot,  and  so 
to  gain  comprehension  of  what  the  essence  of  Mars  con- 
sists. Without  such  background  always  omnipresent 
in  the  picture,  the  lesser  and  more  pregnant  features  fail 
of  effect  in  their  true  value  for  want  of  setting  off.  To 
conceive  of  this  great  buckler  of  brazen  sand  and 
rock,  level  as  a  polished  shield,  and  stretching  to  the 
far  distance,  to  stand  sharp-cut  there  by  the  horizon 


MARS  AND  FUTURE  OF  EARTH   135 

of  a  sky,  unrelieved  by  so  much  as  mountain-notching 
of  its  blue,  is  to  realize  in  part  what  life  on  it  must 
mean.  Where  days  and  months  of  travel  would  bring 
one  no  nearer  to  its  edge,  despair  might  well  settle  on 
the  mind.  And  the  sun  in  its  daily  course  rises  from 
out  the  stony  waste  only  to  set  in  it  again. 

Pitiless  indeed,  yet  to  this  condition  the  earth  itself  HOW  the 
must  come,  if  it  last  so  long.     With  steady,  if  stealthy,  j^J^  fol~ 
stride,  Saharas,  as  we  have  seen,  are  even  now  possess- 
ing themselves  of  its  surface.     The  outcome  is  doubt- 
less yet  far  off,  but  it  is  as  fatalistically  sure  as  that  to- 
morrow's sun  will  rise,  unless  some  other  catastrophe 
anticipate  the  end.     It  is  perhaps  not  pleasing  to  learn 
the  manner  of  our  death.     But  science  is  concerned 
only  with  the  fact,  and  Mars  we  have  to  thank  for  its 
presentment. 

Before  the  final  stage  in  the  long  life  drama  of  a 
planet  is  thus  brought  to  its  close,  there  will  come 
a  time  when  the  water,  having  left  the  surface,  still 
lingers  for  a  little  in  the  air.  For  the  atmosphere  is 
the  pathway  the  water  takes  to  the  sky.  Insufficient 
in  amount  to  leave  a  surplus  on  the  ground  in  the 
shape  of  oceans,  or  even  lakes  and  ponds,  a  certain 
quantity  will  still  hover  up  above.  I  From  the  mode 
of  its  withdrawal,  a  planet  mustTose  its  surface  water 
long  before  it  loses  the  aqueous  vapor  from  its  air,  so 
that  the  absence  of  the  one  argues  nothing  against  the 


136      MARS  AS   THE  ABODE   OF   LIFE 

presence  of  the  other.  Now  there  are  physical  reasons 
connected  with  evaporation  which  would  make  for 
more  water  in  the  air  of  Mars  than  of  the  earth,  and 
yet  not  permit  of  precipitation. 

In  Chapter  III  we  marshalled  the  evidence  we  have 
that  water  exists  on  the  surface  of  Mars :  in  the  polar 
caps  and  practically  nowhere  else.  We  have  now  to 
see  what  proof  there  is  that  it  still  exists  in  the  Martian 
air.  The  evidence  on  which  this  rests  is  twofold:  the 


EFFECT  OF  THE  SPRING  MIST  AROUND  THE  NORTH  POLAR  CAP  OF  MARS 
Drawn  January  25,  1905  (Martian  date,  June  23). 

first  telescopic,  in  the  aspect  of  the  disk.  Water- vapor, 
as  such,  of  course,  we  could  not  expect  to  see,  as  it  is 
invisible  constitutionally.  But  when,  suspended  in  the 
air  it  condenses  into  drops  or  spicules,  we  might  hope 
foi  detection.  Such  proves  a  possibility  occasionally 
on  Mars. 

water  present  As  the  North  polar  cap  melts,  there  comes  a  season 
when  an  indefinite  pearly  appearance  fringes  its  edge, 
obliterating  its  contours,  which  before  were  sharp. 
This  persists  for  some  weeks,  off  and  on,  and  when  at 


in  the  Mar- 
tian atmos- 


MARS  AND  FUTURE  OF  EARTH   137 

last  it  clears,  the  cap  is  seen  to  be  reduced  to  its  least 
extent.  That  it  is  mist  caused  by  the  melting  of  the 
cap  there  is  little  doubt. 

But  there  is  another  instrument  of  astronomical  re- 
search the  special  field  of  which  is  the  study  of  the 
invisible.  To  see  indirectly  what  cannot  be  seen  direct 
is  the  province  of  the  spectroscope.  The  spectroscope 
consists  of  a  prism  or  train  of  prisms  which  disperse 
white  light  into  a  rainbow-tinted  ribbon  known  as  the 
spectrum,  made  up  of  rays  of  different  wave-length  from 
violet  at  one  end  to  red  at  the  other.  Now  it  is  a 
property  of  a  gas,  through  which  light  passes,  to  absorb 
certain  of  the  rays  peculiar  to  itself,  and  so  form  dark 
lines  across  the  spectrum  at  those  points.  Most  of 
the  lines  thus  observed  in  the  solar  spectrum  come 
from  gases  in  the  photosphere  of  the  sun,  but  there 
are  certain  others  which  arise  in  our  own  atmospheric 
envelope  and  are  called  telluric  lines  in  consequence. 
Such  are  the  oxygen  and  water-vapor  bands.  If  now 
another  planet,  such  as  Mars,  possessed  either  of  these 
gases  in  its  atmosphere,  the  light  reflected  from  it 
should  disclose  the  fact  by  deepening  these  bands. 
Much  was  hoped  from  the  spectroscope  on  this 
point. 

Up  to  and  beyond  the  time  when  the  lectures  were 
written,  of  which  this  book  is  the  outcome,  the  spec- 
troscope had  not  proved  itself  a  sufficiently  delicate  in- 


138      MARS   AS   THE   ABODE   OF   LIFE 

strument  to  give  other  than  an  uncertain  answer  on  the 
presence  or  absence  of  water-vapor  on  Mars.  Huggins, 
Vogel,  Janssen,  all  thought  to  see  evidence  of  it  there  ; 
Campbell,  with  more  accurate  instruments,  could  find 
none.  Nor  could  any  be  obtained  under  still  more 
favorable  conditions  of  air  and  instrument  at  Flagstaff. 
The  reason  for  inconclusion,  though  unsuspected  at  the 
time,  lay  in  the  position  of  the  bands  in  the  spectrum 
produced  by  water-vapor.  These  begin,  indeed,  in  the 
yellow,  are  present  in  the  orange  and  light  red,  but  are 
broadest  and  darkest  in  the  partially  visible  deep 
red  and  in  the  invisible  spectrum  beyond  it.  These 
strongest  bands  were  beyond  the  appliances  of  the  day 
for  purposes  of  careful  comparison,  while  the  others 
were  not  sufficiently  salient  to  make  delicate  contrasts 
unmistakable. 

In  the  spring  of  1908,  Mr.  V.  M.  Slipher  succeeded 
at  Flagstaff  in  bathing  plates  to  sensitiveness  through 
the  red,  and,  exposing  these  plates  in  the  camera  of  the 
spectroscope,  photographed  the  spectrum  first  of  Mars 
and  then  of  the  moon  at  the  same  altitude  to  well 
beyond  the  point  where  the  great  water-vapor  band 
known  as  "  a  "  lies.  He  took  in  all  eight  such  plates, 
with  the  result  that  the  "  a  "  band  showed  stronger  in 
the  spectrum  of  the  planet  than  in  that  of  the  moon. 
Now  in  the  case  of  the  moon  it  is  through  our  own 
atmosphere  only  that  we  are  looking;  in  the  case  of 


Water-vapor 


MARS  AND  FUTURE  OF  EARTH   139 

Mars,  through  our  own  plus  that  of  Mars.  Any  dif- 
ference between  the  two  must  be  due  to  the  Martian 
air.  A  strengthening,  then,  in  the  expression  of  the 
"a"  bands  denoted  water-vapor  present  in  the  atmos- 
phere of  Mars.  'Here  we  have  the  much-desired 
spectroscopic  proof,  and  with  it  the  explanation  of  why 
so  much  uncertainty  existed  among  eminent  spectro- 
scopists  before.  To  those  versed  in  Mars  it  is  chiefly 
of  the  nature  of  corroboration.  For  to  the  mind's  eye 
reasoning  had  already  revealed  that  water-vapor  must 
be  there,  but  now  the  bodily  eye  of  any  one  may  see. 
The  thing  is  curiously  paralleled  by  the  way  in  which 
Clerk  Maxwell's  analysis  showed  the  rings  of  Saturn 
to  be  made  of  discrete  particles  before  the  spectroscope 
in  Keeler's  ingenious  hands  stamped  its  evidence  on  a 
photographic  plate. 

That  water-vapor  exists  in  the  air  is  cause  for  its 
deposition  on  the  ground.  But  to  be  precipitated  and 
to  stay  so  are  two  very  different  things.  The  only 
way  in  which  so  scant  an  amount  could  remain  de- 
posited in  any  part  of  the  planet  would  be  as  frozen 
moisture  about  the  pole.  For  as  snow  it  stays 
fixed,  evaporation  at  a  low  temperature  going  so 
much  less  fast  than  from  water  under  its  appropriate 
higher  one.  A  snow-field  suitably  situated  might  thus 
persist  while  a  pond  would  speedily  disappear.  The 
polar  snows  would  be  the  only  place  where  moisture 


i4o      MARS  AS  THE  ABODE   OF   LIFE 

could  descend  to  the  surface  to  stay,  being  brought  to 
the  polar  regions  by  the  planetary  winds. 

With  regard  to  the  distribution  of  the  humidity, 
what  scant  moisture  the  desert-born  equatorial  winds 
might  possess  would  be  deposited  northward  as  they 
cooled,  in  part  impermanently  in  the  forties,  in  part 
more  permanently  at  the  poles.  The  return  flow  of 
air  in  winter,  being  steadily  warmed,  would  not  tend  to 
deposit  moisture  down  the  disk  ;  nor  in  summer  either, 
to  any  extent,  although  from  the  melting  of  the  cap 
such  winds  would  then  be  more  charged  with  vapor. 
Unlike  our  own  earth,  therefore,  moisture  would  pro- 
ceed poleward,  to  remain  there.  Not  only,  therefore, 
is  the  water  much  less  in  amount  on  Mars,  but  what 
is  there  tends  to  be  kept  about  the  poles.  The  only 
available  supply  lies  in  the  arctic  and  antarctic  regions, 
stationary  on  the  ground  or  else  is  in  process  of  jour- 
neying round  to  it  again. 

In  this  last  stage  of  temporizing,  the  water  that 
once  as  such  bespread  Mars's  face  now  is.  The  well- 
nigh  total  disappearance  of  the  one  cap,  and  the  entire 
extinction  of  the  other,  show  how  each  summer  melts 
what  the  winter  had  deposited,  and  that  in  both  cases 
this  is  nearly  the  sum  total  of  the  cap.  Covering  as 
each  does  so  much  territory,  one  might  suppose  the 
water  not  scanty,  but  comparable  in  quantity  to  the 
earth's  supply.  If  we  calculate  it,  however,  we  shall 


MARS  AND  FUTURE  OF  EARTH   141 

find  this  anything  but  the  case.  At  Point  Barrow,  in 
Alaska,  in  latitude  71°  N.,  where  the  temperature  is  be- 
low freezing  from  September  i  to  June  15,  75  inches 
of  snow  fall  during  the  nine  and  a  half  months. 
Ten  inches  of  snow  are  equal  to  one  inch  of  water. 
This  quantity,  then,  measures  the  amount  of  the 
Earth's  impermanent  cap,  and  forms  a  basis  for  com- 
parison with  the  depth  of  the  snow-cap  melted  on 
Mars.  It  seems,  too,  not  an  improbable  value  for 
what  occurs  there ;  for  though  on  the  one  hand  it  is 
likely  that  day  by  day  the  snowfall  is  greater  at  Point 
Barrow  than  on  Thyle,  in  Mars,  at  the  same  latitude, 
on  the  other,  the  winter  season  is  there  twice  as  long. 
To  be  lavish,  we  may  estimate  that  the  equivalent  of 
100  inches  of  snow  fall  on  Thyle.  That  would  mean 
10  inches  of  water.  Now,  the  southern  cap  of  Mars, 
the  larger  of  the  two,  covers  96°  across  at  its 
greatest,  which  makes  its  area  equal  to  one-fifth  of  the 
whole  surface  of  the  planet.  To  this  we  need  not  add 
the  other  cap,  since  it  at  the  time  stretches  over  only 
6°,  a  vanishing  quantity  in  comparison.  On  earth, 
oceans  cover  72  per  cent  of  the  surface,  and  are,  on 
the  average,  2100  fathoms  deep.  Calculation  from 
these  data  gives  the  amount  of  water  on  the  earth  as 
189,000  times  that  on  Mars.  We  said  rightly,  then, 
that  Mars  was  badly  off  for  water. 

In  consequence  of  this   state  of  things,  the  water- 


i42      MARS  AS  THE  ABODE   OF   LIFE 


The  surface 
of  Mars  a 
waterless 
world. 


supply  of  the  planet  is  both  scant  in  amount  and  teth- 
ered at  that.  For  it  is  tied  up  during  the  greater  part 
of  the  year  at  one  pole  or  the  other.  For  a  few  weeks 
only  of  each  six  months  it  stands  unlocked,  first  in 
the  arctic,  then  in  the  antarctic,  zone.  Then,  and  then 
only,  may  this  deposit,  meagre  as  it  is,  be  drawn  upon. 
Mars  is  indebted  for  the  staff  of  life  to  a  polar  pittance 
sparsely  doled  out,  and  that  only  at  appointed  times. 

Study  of  the  natural  features  of  the  planet  leaves  us, 
then,  this  picture  of  its  present  state  —  a  world-wide 
desert  where  fertile  spots  are  the  exception,  not  the 
rule,  and  where  water  everywhere  is  scarce.  So  scanty 
is  this  organic  essential,  that  over  the  greater  part  of 
the  surface  there  is  none  to  quicken  vegetation  or  to 
support  life.  Only  here  and  there  by  nature  are  pos- 
sible those  processes  which  make  our  earth  the  habit- 
able, homelike  place  we  know.  In  our  survey  of 
Mars,  then,  we  behold  the  saddening  picture  of  a 
world  athirst,  where,  as  in  our  own  Saharas,  water  is 
the  one  thing  needful,  and  yet  where  by  nature  it  can- 
not be  got.  But  one  line  of  salvation  is  open  to  it, 
and  that  lies  in  the  periodic  unlocking  of  the  remnant 
of  water  that  each  year  gathers  as  snow  and  ice  about 
its  poles. 

A  high  type         The  evidence  of  observation    thus  bears  out  what 

of  hfe probable  we  mignt  suspect  from  the  planet's  smaller  size  :  that 

it  is  much  farther  along  in  its  planetary  career  than  is 


MARS   AND   FUTURE   OF   EARTH      143 

our  earth.  This  aging  in  its  own  condition  must  have 
its  effect  upon  any  life  it  may  previously  have  brought 
forth.  That  life  at  the  present  moment  would  be 
likely  to  be  of  a  high  order.  For  whatever  its  actual 
age,  any  life  now  existent  on  Mars  must  be  in  the  land 
stage  of  its  development,  on  the  whole  a  much  higher 
one  than  the  marine.  But,  more  than  this,  it  should 
probably  have  gone  much  farther  if  it  exist  at  all,  for 
in  its  evolving  of  terra  firma,  Mars  has  far  outstripped 
the  earth.  Mars's  surface  is  now  all  land.  Its  forms 
of  life  must  be  not  only  terrestrial  as  against  aquatic, 
but  even  as  opposed  to  terraqueous  ones.  They  must 
have  reached  not  simply  the  stage  of  land-dwelling, 
where  the  possibilities  are  greater  for  those  able  to  em- 
brace them,  but  that  further  point  of  pinching  poverty 
where  brain  is  needed  to  survive  at  all. 

The  struggle  for  existence  in  their  planet's  decrepi- 
tude and  decay  would  tend  to  evolve  intelligence  to 
cope  with  circumstances  growing  momentarily  more 
and  more  adverse.  But,  furthermore,  the  solidarity 
that  the  conditions  prescribed  would  conduce  to  a 
breadth  of  understanding  sufficient  to  utilize  it.  Inter- 
communication over  the  whole  globe  is  made  not  only 
possible,  but  obligatory.  This  would  lead  to  the 
easier  spreading  over  it  of  some  dominant  creature,  — 
especially  were  this  being  of  an  advanced  order  of  in- 
tellect,—  able  to  rise  above  its  bodily  limitations  to 


H4      MARS   AS   THE   ABODE   OF   LIFE 

amelioration  of  the  conditions  through  exercise  of 
mind.  What  absence  of  seas  would  thus  entail, 
absence  of  mountains  would  further.  These  two  ob- 
stacles to  distribution  removed,  life  there  would  tend 
the  quicker  to  reach  a  highly  organized  stage.  Thus 
Martian  conditions  themselves  make  for  intelligence. 
The  probabii-  Our  knowledge  of  it  would  likewise  have  its  likeli- 
Maraatthe"  no°d  increased.  Not  only  could  any  beings  there  dis- 
present  time,  dose  their  presence  only  through  their  works,  but 
from  the  physical  features  the  planet  presents,  we  are 
led  to  believe  that  such  disclosure  would  be  distinctly 
more  probable  than  in  the  case  of  the  earth.  Any 
markings  made  by  mind  should  there  be  more  defi- 
nite, more  uniform,  and  more  widespread  than  those 
human  ones  with  which  we  are  familiar.  More  domi- 
nant of  its  domicile,  it  should  so  have  impressed  itself 
upon  its  habitat  as  to  impress  us  across  intervening 
space. 

What  the  character  of  such  markings  might  be,  we 
shall  best  conceive  by  letting  the  pitiless  forbiddingness 
of  the  Martian  surface  take  hold  upon  our  thought. 
Between  the  two  polar  husbandings  of  the  only  water 
left,  stands  the  pathless  desert  —  pathless  even  to  the 
water  semiannually  set  free.  Only  overhead  does  the 
moisture  find  natural  passage  to  its  winter  sojourn  at 
the  other  pole.  Untraversable  without  water  to 
organic  life,  and  uninhabitable,  the  Sahara  cuts  off 


MARS   AND   FUTURE   OF    EARTH      145 

completely  the  planet's  hemispheres  from  each  other, 
barring  surface  commerce  by  sundering  its  supplies. 
Thirst —  the  thirst  of  the  desert  —  comes  to  us  as  we 
realize  the  situation,  parching  our  throat  as  we  think 
of  a  thirst  impossible  of  quenching  except  in  the  far- 
off  and  by  nature  unattainable  polar  snows. 

Turning  again  to  Mars  with  quickened  sense,  we 
witness  an  astounding  thing,  the  study  of  which  in  its 
mien,  its  moods,  and  its  meaning,  the  next  two  chap- 
ters will  take  up. 


CHAPTER  V 

THE    CANALS    AND    OASES    OF    MARS 

A  •  AHIRTY  years  ago  what  were  taken  for  the  con- 
-I-      tinents  of  Mars  seemed,  as  one  would  expect 
continents  seen  at  such  a  distance  to  appear,  virtually 
featureless. 

Schiapareiii  In   1 877,  however,  a  remarkable  observer  made  a 

he  canals.  gtjjj  more  remarkable  discovery ;  for  in  that  year 
Schiapareiii,  in  scanning  these  continents,  chanced 
upon  long,  narrow  markings  in  them  which  have 
since  become  famous  as  the  canals  of  Mars.  Sur- 
prising as  they  seemed  when  first  imperfectly  made 
out,  they  have  grown  only  more  wonderful  with 
study.  It  is  certainly  no  exaggeration  to  say  that 
they  are  the  most  astounding  objects  to  be  viewed  in 
the  heavens.  There  are  celestial  sights  more  dazzling, 
spectacles  that  inspire  more  awe,  but  to  the  thoughtful 
observer  who  is  privileged  to  see  them  well  there  is 
nothing  in  the  sky  so  profoundly  impressive  as  these 
canals  of  Mars.  Fine  lines  and  little  gossamer  fila- 
ments only,  cobwebbing  the  face  of  the  Martian  disk,, 
but  threads  to  draw  one's  mind  after  them  across  the 
millions  of  miles  of  intervening  void. 

Although  to  the  observer  practised  in  their  detec- 
tion they  are  at  certain  times  not  only  perfectly  dis- 
146 


THE   CANALS   AND   OASES   OF   MARS    147 

tinct,  but  are  not  even  difficult  objects,  —  being  by  no 
means  at  the  limit  of  vision,  as  is  often  stated  from 
ignorance,  —  to  one  not  used  to  the  subject,  and 
observing  under  the  average  conditions  of  our  trouble- 
some air,  they  are  not  at  first  so  easy  to  descry.  Had 
they  been  so  very  facile,  they  had  not  escaped  detec- 
tion so  long,  nor  needed  Schiaparelli,  the  best  observer 
of  his  day,  to  discover  them.  But  in  good  air  they 
stand  out  at  times  with  startling  abruptness.  I  say 
this  after  having  had  twelve  years'  experience  in  the 
subject  —  almost  entitling  one  to  an  opinion  equal  to 
that  of  critics  who  have  had  none  at  all. 

How  beside  the  mark  it  is  to  credit  them  to  illusion 
may  at  once  be  appreciated  from  the  fact  that  experi- 
ment shows  the  main  ones  to  appear  through  the  tele- 
scope of  the  same  size  as  a  telegraph  wire  seen  with  the 
naked  eye  at  a  distance  of  a  hundred  and  fifty  feet. 
But  if  the  air  be  not  steady,  they  are  blurred  almost 
out  of  recognition. 

With  our  air  at  its  best,  the  first  thing  to  strike  one 
in  these  strange  phenomena  is  their  geometric  look. 
It  has  impressed  every  observer  who  has  seen  them 
well.  It  would  be  hard  to  determine  to  which  of 
their  peculiar  characteristics  this  effect  was  specially 
due.  Indeed,  it  is  probably  attributable  to  their  com- 
bination ;  for  distinctive  as  each  trait  is  alone,  their 
summation  is  multiplicitly  telling.  That  the  lines  run 


148      MARS   AS   THE  ABODE   OF   LIFE 

quite  straight  from  point  to  point — that  is,  on  arcs  of 
great  circles,  or  else  curve  in  an  equally  determinate 
manner ;  that  they  are  of  uniform  width  throughout ; 
that  their  tenuity  is  extreme  and  that  they  are  of 
enormous  length,  are  attributes  each  of  which  is  geo- 
metrically startling  and  which,  taken  together,  enhance 
this  in  geometric  ratio. 

Lines  are  That    the    lines    are    absolutely    straight  —  which 

means  that  on  a  sphere  like  Mars'  they  follow  arcs 
of  great  circles  —  is  shown  by  two  facts  which  fay 
into  one  another.  One  of  these  is  that  they  look 
straight  to  the  observer  when  central  enough  not  to 
have  foreshortening  tell.  This  could  not  happen 
unless  they  were  the  shortest  possible  lines  between 
their  termini.  The  other  proof  consists  in  their  fitting 
together  to  form  a  self-agreeing  whole  when  the  result 
of  all  the  drawings  —  hundreds  in  number  at  each 
opposition  —  are  plotted  on  a  globe. 

In  regard  to  their  width,  it  would  be  nearest  the 
mark  to  say  that  they  had  none  at  all.  For  they 
have  been  found  narrower  and  narrower  as  the  con- 
ditions of  scanning  have  improved.  By  careful  ex- 
periments at  Flagstaff  it  has  been  shown  that  the 
smallest  appear  as  they  should  were  they  but  a  mile 
across.  The  reason  so  slender  a  filament  is  visible  is 
due  to  its  length,  and  this  probably  because  of  the 
number  of  retinal  cones  that  are  struck.  Were  only 


HYDE  PARK  AND  PARK  LANE,  LONDON,  1908 
From  a  Free  Balloon. 


From  Photographs  at  2200  feet  by  Profs.  Rotch  and  Lowell 

HYDE  PARK  AND  THE  SERPENTINE 
Showing  Artificial  Markings  of  Earth  seen  from  Space. 


THE   CANALS  AND   OASES   OF   MARS    149 

one  affected,  as  would  be  the  case  were  the  object  a 
point,  it  certainly  could  not  be  detected.16 

So  much  for  the  smallest  canal  now  visible  with  our 
present  means.  The  larger  are  much  more  conspicu- 
ous. These  look  not  like  gossamers,  as  the  little 
ones  do,  but  like  strong  pencil-lines.  Comparison 
with  the  thread  of  the  micrometer  gives  for  the  average 
canal  a  breadth  of  about  ten  miles.  The  canals,  how- 
ever, are  by  no  means  of  a  uniform  width.  Indeed, 
they  are  of  all  sizes,  from  lines  it  would  seem  impos- 
sible to  miss  to  others  it  taxes  attention  to  descry. 

All  the  more  surprising  for  their  relative  diversity 
is  the  remarkably  uniform  size  of  each  throughout  its 
course.  So  far  as  it  is  possible  to  make  out,  there  is 
no  perceptible  difference  in  width  of  a  canal,  when  fully 
developed,  from  one  end  of  it  to  the  other.  Certainly 
it  takes  a  well-ruled  line  on  paper  to  look  its  peer  for 
regularity  and  deportment. 

True  thus  to  itself,  each  canal  differs  from  its  neigh- 
bor not  only  in  width,  but  in  extension.  For  the 
canals  are  of  very  various  length.  Some  are  not  above 
250  miles  long,  while  others  stretch  2500  miles  from 
end  to  end.  Nor  is  this  span  by  any  means  the  limit. 
The  Eumenides-Orcus  runs  3450  miles  from  where  it 
leaves  the  Phoenix  Lake  to  where  it  enters  the  Trivium 
Charontis.  Enormous  as  these  distances  are  for  lines 
which  remain  straight  throughout,  they  become  the 


150      MARS   AS   THE  ABODE   OF   LIFE 

more  surprising  when  we  consider  the  size  of  the 
planet  on  which  they  are  found.  For  Mars  is  only 
4220  miles  through,  while  the  earth  is  7919.  So  that 


\ 


A  SECTION  OF  THE  CANAL  EUMENIDES-ORCUS  TERMINATING  IN  THE 

JUNCTION  TRIVIUM  CHARONTIS 

The  length  of  this  canal  is  3500  miles.  The  remainder  of  the  canal  may  be  seen 
on  the  hemisphere  shown  on  p.  156,  where  it  starts  from  Phrenix  Lake  (Lucus 
Phoenicis). 

a  canal  3450  miles  long,  for  all  its  unswervingness 
to  right  or  left,  actually  curves  in  its  own  plane 
through  an  arc  of  some  90°  round  the  planet. 
It  is  much  as  if  a  straight  line  joined  London  to 
Denver,  or  Boston  to  Bering  Strait. 


THE   CANALS  AND   OASES   OF   MARS    151 

It  should  be  remembered,  however,  that  it  is  the 
actual,  not  the  relative,  length  we  have  really  to 
consider.  But  this  is  surprising  enough  —  more  than 
sufficient  in  the  Eumenides-Orcus  to  span  the 
United  States. 

Odd  as  is  the  look  of  the  individual  canal,  it  is 
nothing  to  the  impression  forced  upon  the  observer 
by  their  number  and  still  more  by  their  articulation. 
When  Schiaparelli  finished  his  life-work,  he  had  de- 
tected 113  canals;  this  figure  has  now  been  increased 
to  437  by  those  since  added  at  Flagstaff.  As  with 
the  discovery  of  the  asteroids,  the  later  found  are  as 
a  rule  smaller  and  in  consequence  less  evident  than 
the  earlier.  But  not  always ;  and,  unlike  asteroid 
hunting,  it  is  not  because  of  easy  missing  in  the  vast 
field  of  sky.  The  cause  is  intrinsic  to  the  canal. 

This  great  number  of  lines  forms  an  articulate 
whole.  Each  stands  jointed  to  the  next  (to  the 
many  next,  in  fact)  in  the  most  direct  and  simple 
manner  —  that  of  meeting  at  their  ends.  But  as 
each  has  its  own  peculiar  length  and  its  special 
direction,  the  result  is  a  sort  of  irregular  regularity. 
It  resembles  lace-tracery  of  an  elaborate  and  elegant 
pattern,  woven  as  a  whole  over  the  disk,  veiling  the 
planet's  face.  By  this  means  the  surface  of  the 
planet  is  divided  into  a  great  number  of  polygons, 
the  areolas  of  Mars. 


152      MARS  AS   THE  ABODE   OF   LIFE 

Schiaparelli  detected  the  existence  of  the  canals 
when  engaged  in  a  triangulation  of  the  planet's  sur- 
face for  topographic  purpose.  What  he  found  was 
a  triangulation  already  made.  In  his  own  words, 
the  thing  "  looked  to  have  been  laid  down  by  rule 
and  compass."  Indeed,  no  lines  could  be  more  pre- 
cisely drawn,  or  more  meticulously  adjusted.  Not 
only  do  none  of  them  break  off  in  mid-career,*  to 
vanish,  as  rivers  in  the  desert,  in  the  great  void  of 
ochre  ground,  but  they  contrive  always  in  a  most 
gregarious  way  to  rendezvous  at  special  points,  run- 
ning into  the  junctions  with  the  space  punctuality 
of  a  train  on  time.  Nor  do  one  or  two  only  man- 
age this  precision ;  all  without  exception  converge 
from  far  points  accurately  upon  their  centres.  The 
meetings  are  as  definite  and  direct  as  is  possible  to 
conceive.  None  of  the  large  ochre  areas  escapes 
some  filament  of  the  mesh.  No  single  secluded  spot 
upon  them  could  be  found,  were  one  inclined  to 
desert  isolation,  distant  more  than  three  hundred 
miles  from  some  great  thoroughfare. 

For  many  years  —  in  fact,  throughout  the  period 
of  observation  of  the  great  Italian  —  the  canals  were 
supposed  to  be  confined  to  the  bright  or  reddish 
ochre  regions  of  the  disk.  None  had  been  seen  by 

*  Their  seeming  occasionally  to  do  so  is  due  to  their  mode  of  growth  seasonally 
or  to  certain  latitudes  being  better  shown  than  others  at  the  time. 


THE   CANALS   AND   OASES   OF   MARS    153 

him  elsewhere,  and  none  was  divined  to  exist.  But 
in  1892,  W.  H.  Pickering,  at  Arequipa,  saw  lines 
in  the  dark  regions;  and,  in  1894,  Douglass,  at  Flag- 
staff, definitely  detected  the  presence  of  a  system  of 
canals  criss-crossing  the 
blue-green  similar  to  that 
networking  the  ochre. 
Later  work  at  Flagstaff 
has  shown  all  the  dark 
areas  to  be  thus  seamed 
with  lines,  and  lastly  has 
brought  out  with  emphasis 
the  pregnant  fact  that 
these  are  continued  by 
others  connecting  with  the 

polar  snows.*  Thus  the  system  is  planet-wide  in 
its  application,  while  it  ends  by  running  up  to  the 
confines  of  the  polar  cap.  The  first  gives  it  a 
generality  that  opened  up  new  conceptions  of  its 
office,  the  second  vouchsafes  a  hint  as  to  its  origin. 
For  many  years  the  pioneers  in  this  discovery  of 
another  world  had  their  revelations  strictly  to  them- 
selves, decried  as  baseless  views  and  visions  by  the 
telescopically  blind.  So  easily  are  men  the  dupes  of 


*  Previous  to  1907  the  fact  was  known  only  for  the  northern  hemisphere.  In 
1907  the  Flagstaff  observations  disclosed  the  important  extension  of  the  scheme 
through  the  antarctic  zone  j  a  striking  confirmation  of  theory. 


CANALS  IN  DARK  REGIONS  CON- 
NECTING WITH  THE  POLAR  CAP 


i54      MARS  AS  THE   ABODE   OF   LIFE 


their  own  prejudice.  But  in  1901  attempts  began  to 
be  made  at  Flagstaff  to  make  them  tell  their  own 
story  to  the  world,  writing  it  by  self-registration  on 

a  photographic 
plate.  It  was 
long  before 
they  could  be 
compelled  tc 
do  so.  The 
first  attempts 
showed  noth- 
ing; the  next, 
two  years  later, 
did  better, 
evoking  faint 
forms  to  the 
initiate,  but  to 
them  alone;  but 
two  years  later 
still,  success 
crowned  the 
long  endeavor.  At  last  these  strange  geometricisms 
have  stood  successfully  for  their  pictures.  The  photo- 
graphic feat  of  making  them  keep  still  sufficiently 
long  —  or,  what  with  heavenly  objects  is  as  near  as 
man  may  come  to  his  practice  with  human  subjects, 
the  catching  of  the  air-waves  still  long  enough  to 


PHOTOGRAPHIC  APPARATUS  OF  THE  LOWELL 

OBSERVATORY 

Devised  by  Mr.  C.  O.  Lampland,  and  used  in  getting 
the  photographs  of  the  canals  of  Mars. 


THE   CANALS   AND   OASES   OF   MARS    155 

secure  impression  of  them  upon  a  photographic  plate 
—  has  been  accomplished  by  Mr.  Lampland.  After 
great  study,  patience,  and  skill  he  has  succeeded  in 
this  remarkable  performance,  of  which  Schiaparelli 
wrote  in  wonder  to  the  present  writer  :  "  I  should 
never  have  believed  it  possible." 

Regard  for  positioning  is  one  of  the  most  signifi- 
cant characteristics  of  the  lines.  They  join  all  the 
salient  points  of  the  surface  to  one  another.  If  we 
take  a  map  of  the  planet  and  connect  its  prominent 
landmarks  by  straight  lines,  we  shall  find,  to  our 
surprise,  that  we  have  counterfeited  the  reality.  That 
they  are  so  regardant  of  topography  on  the  one  hand, 
and  so  regardless  of  terrain  on  the  other,  gives  a 
most  telltale  insight  into  their  character ;  it  shows 
that  they  are  of  later  origin  than  the  main  markings 
themselves.  For  they  bear  testimony  to  this  without 
regard  to  what  they  are.  Their  characteristics  and 
their  attitudes,  in  short,  betray  that  at  some  time 
subsequent  to  the  fashioning  of  the  planet's  general 
features  the  lines  were  superposed  upon  them. 

But  this  is  not  all.     Since  the  seas  probably  were  Canals  super- 
seas  in  function  as  in    name    once  upon  a  time,  the  pose 

r  mam  features. 

superposition  must  have  occurred  after  they  ceased 
to  be  such  ;  for  clearly  the  lines  could  not  have  been 
writ  on  water,  and  yet  be  read  to-day.  We  are 
thus  not  only  furnished  with  a  datum  about  the 


156      MARS   AS   THE  ABODE   OF   LIFE 

origin  of  the  canals,  but  with  a  date  determining 
when  it  took  place.  The  date  marks  a  late  era  in 
the  planet's  development,  one  subsequent  to  any  the 


HEMISPHERE  SHOWING  THE  OASIS  CALLED  ASCRAEUS  Lucus 


From  this  radiate  many  canals.    Also  in  the  upper  right-hand  space  is  shown  the 
continuation  of  the  Eumenides-Orcus. 

earth  has  yet  reached.     This  accounts    for    the  diffi- 
culty found  in   understanding    them,  for    as    yet    we 
have  nothing  like  them  here. 
Oases.  Next  in    interest    to    the    canals    come    the    oases. 


THE   CANALS   AND   OASES   OF   MARS    157 

Many  years  after  the  detection  of  the  canals,  scrutiny 
revealed  another  class  of  detail  upon  the  planet  of 
an  equally  surprising  order.  This  was  the  presence 
there  of  small,  round,  dark  spots  dotted  over  the 
surface  of  the  disk.  Seen  in  any  number,  first  by 
W.  H.  Pickering  in  1892,  they  lay  at  the  meeting- 
places  of  the  canals.  He  called  them  lakes.  Some 
few  had  been  caught  earlier,  but  were  not  well 
recognized.  We  now  know  186  of  them,  and  we 
are  very  certain  they  are  not  lakes.  In  the  case  of 
one  of  them,  the  Ascraeus  Lucus,  no  less  than  sev- 
enteen canals  converge  to  it. 

It  thus  appears  that  the  spots  make,  as  it  were,  the 
knots  of  the  canal  network.  They  emphasize  the 
junctions  in  look  and  at  the  same  time  indicate  their 
importance  in  the  system.  For  just  as  no  spot  but 
stands  at  a  junction,  so,  reversely,  few  prominent  junc- 
tions are  without  a  spot,  and  the  better  the  surface  is 
seen,  the  more  of  these  junctions  prove  to  be  provided 
with  them. 

Their  form  is  equally  demonstrative  of  their  func- 
tion. They  are  apparently  self-contained  and  self- 
centred,  being  small,  dark,  and,  as  near  as  can  be 
made  out,  round.  It  is  certain  that  they  are  not 
mere  reinforcements  of  the  canals  due  to  cross- 
ing, for  crossings  do  occur  where  none  are  seen, 
while  the  lines  themselves  are  perfectly  visible,  and 


158      MARS   AS   THE   ABODE   OF   LIFE 

of  the  same  strength  at  the  crossing  as  before  and 
after. 

We  now  come  to  a  yet  more  surprising  detail. 
The  existence  of  the  single  canals  had  scarcely  been 
launched  upon  a  world  quite  unprepared  for  their 
reception,  and  duly  distant  in  their  welcome  in  con- 
sequence, before  that  world  was  asked  to  admit  some- 
thing more  astounding  still ;  namely,  that  at  certain 
times  some  of  these  canals  appeared  mysteriously 
paired,  the  second  line  being  an  exact  replica  of  the 
first,  running  by  its  side  the  whole  of  its  course,  how- 
ever long  this  might  be,  and  keeping  equidistant  from 
it  throughout.  The  two  looked  like  the  twin  rails 
of  a  railway  track.  (See  map  opposite  page  217.) 

To  begin  by  giving  an  idea  of  the  phenomenon,  I 
will  select  a  typical  example,  which  happened  also  to- 
be  one  of  the  very  first  observed  by  me  —  that  of  the 
great  Phison.  The  Phison  is  a  canal  that  runs  for  2250 
miles  between  two  important  points  upon  the  planet's 
surface,  the  Portus  Sigaeus,  halfway  along  the  Mare 
Icarium,  and  the  Pseboas  Lucus,  just  off  the  Proto- 
nilus.  In  this  long  journey  it  traverses  some  six 
degrees  of  the  southern  hemisphere  and  about  forty 
degrees  of  the  northern.  In  1894  the  canal  was  first 
seen  as  a  single,  well-defined  line  —  not  a  line  that 
admitted  of  haziness  or  doubt,  but  which  was  as 
strictly  self-contained  and  slenderly  distinguished  as 


THE   CANALS   AND   OASES   OF   MARS    159 

any  other  single  canal  on  the  planet.  A  Martian 
month  or  more  after  it  thus  expressed  itself,  it 
suddenly  stood  forth  an  equally  self-confessed  double, 
two  parallel  lines  replacing  the  solitary  line  of  some 
months  before.  Not  the  slightest  difference  in  the 
character,  direction,  or  end  served  was  to  be  detected 
between  the  two  constituents.  Just  as  certainly  as  a 
single  line  had  shown  before,  a  double  line  now  showed 
in  its  stead. 

Study  of  the  doubles  has  been  prosecuted  for  some 
years  now  at  Flagstaff,  and  its  prosecution  has  gradu- 
ally revealed  more  and  more  of  their  peculiarities 
The  first  thing  this  study  of  the  subject  has  brought 
out  is  that  duality,  bilateralism,  is  not  a  universal 
feature  of  the  Martian  canals.  Quite  the  contrary. 
It  cannot  be  said  in  any  sense  to  be  even  a  general 
attribute  of  them.  The  great  majority  of  the  canals 
never  show  double  at  any  time,  being  persistently  and 
perpetually  single.  Out  of  the  437  canals  so  far  dis- 
covered, only  51  have  ever  shown  duplicity.  From 
this  we  perceive  that  less  than  one-eighth  of  all  the 
canals  visible  affect  the  characteristic,  nor  are  these  51 
distinguished  in  any  manner,  by  size  or  position,  from 
those  of  the  other  386  that  remain  pertinaciously 
single.  They  are  neither  larger  nor  smaller,  longer 
nor  shorter,  nor  anything  else  which  would  suffice  on 
a  superficial  showing  to  distinguish  their  strange  in- 


Width  differs 
for  different 
doubles. 


160      MARS   AS   THE   ABODE   OF   LIFE 

herent  potentiality  from  that  of  those  which  do   not 

possess  the  property. 

Now,    this    fact    directly    contradicts    every    optical 

theory  of  their  formation.  If  the  doubles  were  prod- 
ucts of  any  optical  law,  that 
law  should  apply  to  all  canals 
alike,  except  so  far  as  posi- 
tion, real  or  relative  upon 
the  disk,  might  affect  their 
visibility.  Now,  the  double 
canals  are  not  distinguished 
in  any  of  these  ways  from 
their  single  sisters.  They 
run  equally  at  all  sorts  of 

angles  to  the  meridian,  and  are  presented  equally  at 

all  sorts  of  tilts  to  the  observer ;  and  yet  the  one  kind 

keeps  to  its  singularity,  and  the  other  to  its  preference 

for       the       paired 

estate. 

The  next  point  y- 

is   that    the  width 

of  the  gemination  •  * 

—  the       distance, 

that     is,     between 

the       constituents       L~ 

r       i               .  .  A  MASS  OF  DOUBLE  CANALS,  ELYSIUM  (SHE 

or      the      pair IS  THE  HEMISPHERE,  PAGE  150) 

not     the     Same     for  From  a  drawing  made  on  June  i,  1903. 


SINGLE  AND  DOUBLE  CANALS 
In  a  drawing  made  July  15,  1905. 


t 


THE   CANALS   AND   OASES   OF   MARS    161 


all  the  doubles.  Indeed,  it  varies  enormously.  Thus, 
we  have  at  one  end  of  the  list  the  little,  narrow  Djihoun, 
the  constituents  of  which  are  not  separated  by  more 
than  two  degrees ;  while  at  the  other  end  stands  the 
Nilokeras,  with  its  members  eleven  degrees  apart. 
That  is,  we  have  a  parallelism  of  seventy-five  miles  in 
one  case,  and  one  of  four  hundred  in  another.  This 
fact  disposes  again  of  any  optical  or  illusory  production 
of  the  lines ;  for  were  their  origin  such,  they  would  all 
be  of  the  same  width. 

Position  is  the  next  thing  to  be  considered.  A 
general  investigation  of  this  shows  some  results  whidi 
are  highly  in- 
structive. To 
begin  with,  the 
distribution  of 
the  doubles  may 
be  broadly 
looked  at  from 
two  points  of 


view,     that     of 


A  MASS  OF  SINGLE  CANALS  ABOUT  Lucus 
PHOENICIS  (SEE  THE  HEMISPHERE,  PAGE  156) 

From  a  drawing  made  in  November,  1894. 


their  longitudi- 
nal or  latitudinal 
placing  upon  the  planet.  Considering  the  longitudinal 
first,  if  we  cut  the  planet  in  halves,  the  one  hemi- 
sphere extending  from  longitude  20°  to  200°  and 
the  other  from  200°  to  20°,  more  than  two-thirds  of 


162      MARS   AS   THE  ABODE   OF   LIFE 

all  the  double  canals  turn  out  to  lie  in  the  second 
section  ;  the  numbers  being  fifteen  in  the  one  to 
thirty-six  in  the  other.  It  appears,  then,  that  the 
doubles  are  not  evenly  distributed  around  the 
planet. 

We  now  turn  to  their  partition  according  to  latitude, 
and  here  we  are  made  aware  of  a  significant  distribu- 
tion affecting  them.  If  we  divide  the  surface  into 
zones  of  ten  degrees  each,  starting  from  the  equator 
and  travelling  in  either  direction  to  the  pole,  and 
count  the  double  canals  occurring  in  each,  we  note  a 
marked  falling  off  in  their  number  after  we  leave  the 
tropic  and  subtemperate  zones,  and  a  complete  cessa- 
tion of  them  at  latitude  63°  north.  The  actual  num- 
bers are  as  follows  :  — 

Between  90°  S.   and  30°  S o 

Between  30°  S.  and  20°  S 3 

Between  20°  S.  and  10°  S 9 

Between    10°  S.   and     o° 20 

Between     o°         and  IO°  N 29 

Between  10°  N.  and  20°  N 26 

Between  20°  N.  and  30°  N 23 

Between  30°  N.  and  40°  N 20 

Between  40°  N.  and  50°  N 4 

'  Between  50°  N.  and  60°  N 3 

Between  60°  N.  and  63°  N 2 

Between  63°  N.  and  90°  N o 


THE   CANALS   AND   OASES   OF   MARS    163 

As  a  double  may  pass  through  more  than  one  zone,  it 
may  be  counted  more  than  once,  which  explains  the  total 
in  the  table,  though  the  doubles  number  but  fifty-one. 

Thus  the  doubles  are  tropical  features  of  the  planet,  Area  of  zones, 
not   general    ones.     Decidedly    this    proclaims    again 
their  reality,  for  were  they  optical  only,  they  could  not 
show  such  respect  for  the  equator  —  a  respect  worthy 
of  commendation  from  Sydney  Smith. 

Another  of  their  peculiarities  consists  in  their  being 
confined  to  the  light  regions.  For,  with  one  possible 
exception,  no  doubles  have  been  detected  in  the  dark 
areas  of  the  disk,  whereas  plenty  of  single  canals  have 
been  found  there. 

Yet  to  the  dark  areas  they  stand  somehow  beholden. 
For  the  great  majority  of  them  debouch  from  what  were 
once  thought  seas,  to  traverse  the  great  deserts.  Of  the 
51  doubles,  no  fewer  than  28  are  thus  immediately  con- 
nected with  the  'seas.'  But  this  is  not  the  end  of  the 
dependence.  For  the  remaining  canals,  23  in  number, 
each  connect  with  one  or  other  of  the  doubles  that  per- 
sonally connect  with  these  dark  regions.  In  all  but  two 
cases  the  secondary  dependence  is  direct ;  in  these  two 
a  smaller  dark  patch  occurs  in  the  line  of  the  connection. 

Thus,  the  double  canals  show  a  most  curious  sys- 
tematic dependence  upon  the  great  dark  areas  of  the 
southern  hemisphere.  In  this  they  reproduce  again  the 
general  dependability  of  single  canals  upon  topographic 


1 64      MARS   AS   THE   ABODE   OF   LIFE 

features  ;  but  with  more  emphatic  particularity,  for  they 
prove  that  not  only  are  prominent  points  for  much 
in  their  localization,  but  that  different  kinds  of  terrain 
are  curiously  concerned.  The  relation  of  one  kind  of 
terrain  to  another  is  essential  to  their  existence,  since 
they  are  virtually  not  found  in  the  blue-green  areas,  and 
yet  are  found  in  the  light  only  in  connection  with  the 
blue-green.  That  the  blue-green  is  vegetation  and  the 
ochre  desert  leads  one's  thought  to  conjecture  beyond. 
To  turn,  now,  to  another  mode  of  position,  we 
will  look  into  the  direction  in  which  these  doubles  run. 
To  do  this,  we  shall  segregate  them  according  to  the 
compass-points.  Any  one  of  them,  of  course,  runs 
two  ways  ;  as,  for  example,  N.N.E.  and  S.S.W.,  and 
we  shall  therefore  have  but  half  the  whole  number  of 
compass-points  to  consider.  Taking  the  direction 
two  points  apart,  we  shall  have  eight  sets,  dividing 
the  canals  into  bunches,  as  follows  :  — 

S.  andN ,    1     .     .     .  7 

S.S.E.  and  N.N.W.    .    V    .....  5 

S.E.  and  N.W 4 

E.S.E.  and  W.N.W.       .     .     .     .     .-<  .  3 

E.  and  W 6 

E.N.E.  and  W.S.W 6 

N.E.  andS.W 12 

N.N.E.  and  S.S.W 8 

51 


THE   CANALS   AND   OASES   OF   MARS    165 

At  first,  to  one  considering  this  table,  no  marked 
preponderance  for  one  direction  over  another  mani- 
fests itself  in  the  orientation.  Still,  a  certain  trend  to 
the  east  of  north  as  opposed  to  the  west  of  north  is 
discernible.  For  25  doubles  run  within  45°  of  north- 
east and  southwest,  to  1 2  only  that  do  the  same  thing 
for  northwest  and  southeast.  Following  up  the  hint 
thus  given  us,  we  proceed  to  apportion  the  canals  first 
into  quadrantal  points.  The  result  is  a  fairly  equable 
division  all  around  the  circle.  Now,  as  a  matter  of 
fact,  by  lumping  the  doubles  of  the  two  hemispheres 
together,  we  have  almost  obliterated  a  striking  fact 
which  lies  hidden  in  the  table.  If,  instead  of  thus  com- 
bining them,  we  separate  those  exclusively  of  the  north- 
ern hemisphere  from  those  of  the  southern  one  only, 
and  now  note  in  each  of  these  what  proportion  trend  to 
the  west  of  south  as  against  those  that  run  to  the  east 
of  it,  and  vice  versa,  we  come  out  with  significant  re- 
sults. In  the  northern  hemisphere,  the  proportion  of 
double  canals  to  show  a  westward  trend  as  opposed 
to  an  eastern  is  17  to  4.  In  the  southern  hemisphere, 
the  easterly-trending  outnumber  the  westerly-trending 
by  i  to  o ;  while  for  those  whose  course  is  common 
to  both  hemispheres  we  find  for  the  ratio  of  south- 
western to  southeastern  8  to  7. 

How  can  this  be  explained  ?  Consider  a  particle 
descending  from  the  pole  to  the  equator  under  the 


166      MARS   AS   THE  ABODE   OF  LIFE 

push  of  a  certain  momentum.  As  the  particle  (of 
water,  for  example)  reaches  a  lower  and  lower  latitude, 
it  comes  upon  a  surface  which  is  travelling  faster  and 
faster  eastward,  because,  since  all  parts  of  the  body, 
whether  the  earth  or  Mars,  rotate  in  the  same  time, 
those  particles  where  the  girth  is  greatest  have  the 
farthest  distance  to  go. 

In  consequence  of  this  the  particle  would  con- 
stantly be  going  at  a  less  speed  to  the  east  than 
the  spot  upon  which  it  found  itself  adventured,  and 
so  relatively  to  that  place  would  move  to  the  west. 
From  the  south  pole  to  the  equator,  therefore,  its 
course  would  always  show  a  deviation  southwesterly 
from  a  due  north  and  south  direction. 

In  the  southern  hemisphere,  on  the  other  hand, 
since  the  rotation  of  the  planet  is  the  same,  its  direc- 
tion with  regard  to  the  pole  is  different,  for  the  sur- 
face upon  which  the  particle  successively  comes  still 
sweeps  to  the  east.  It  would,  therefore,  relatively 
to  the  surface,  move  to  the  northwest,  and  we 
should  have  in  this  hemisphere  a  northwesterly  trend 
from  the  pole  equatorward. 

This  is  actually  what  we  see  in  the  doubles  of 
Mars.  The  proportion  of  canals  trending  to  the 
west  as  against  those  trending  to  the  east  in  the 
northern  hemisphere  is,  as  we  have  seen,  17  to  4  ; 
while  in  the  southern  hemisphere  the  proportion 


THE   CANALS  AND   OASES   OF   MARS    167 

trending  to  the  east  is  I  to  o.  As  for  canals  occupy- 
ing both  grounds  a  compromise  is  effected,  the  canals 
running  according  to  the  hemisphere  in  which  the 
greater  part  of  their  course  is  situated.  This  is  cer- 
tainly a  very  curious  conclusion,  and  seems  to  justify 
the  name  canals  as  typifying  a  conduit  of  some  sort 
in  which  something  flowed.17 

Passing  strange  as  is  the  mere  look  of  the  canals,  The  canals 
study  has  disclosed  something  about  them  stranger  ^^^ 
yet :  changes  in  their  aspect  depend  on  the  time. 
Permanent  the  canals  are  in  place,  impermanent  they 
prove  in  character.  At  one  epoch  they  will  be  con- 
spicuous objects,  almost  impossible  to  miss ;  then,  a 
few  months  later,  acuteness  is  taxed  to  discover  them 
at  all.  Nor  is  this  the  whole  story ;  some  will  show 
when  others  remain  hid,  and  others  will  appear  when 
the  first  have  become  invisible.  Whole  regions  are 
affected  by  such  self-effacement  or  an  equal  ostenta- 
tion ;  while  neighboring  ones  are  simultaneously 
given  to  the  reverse. 

Curiously  enough,  the  canals  are  most  con- 
spicuous not  at  the  time  the  planet  is  nearest  to 
the  earth  and  its  general  features  are  in  consequence 
best  seen  ;  but  as  the  planet  goes  away,  the  canals 
come  out.  The  fact  is  that  the  orbital  position 
and  the  seasonal  epoch  conspire  to  a  masking  of 
the  canal  phenomena.  For  the  planet  comes  to  its 


168      MARS   AS   THE   ABODE   OF   LIFE 

closest  approach  to  the  earth  a  little  before  it 
reaches  in  its  orbit  the  summer  solstice  of  its  south- 
ern hemisphere.  For  two  reasons  this  epoch  of 
nearness  is  an  unpropitious  date  for  the  canal  ex- 
hibit :  first,  because  the  bright  areas,  where  the 
canals  are  easiest  made  out,  lie  chiefly  in  the  hemi- 
sphere then  tipped  away  from  the  earth  ;  and 
secondly,  because  it  is  not  the  Martian  season  for 
the  canals  to  show. 

Due  to  this  inopportune  occurrence  of  the  two 
events,  approach  and  seasonableness,  the  canals  lay 
longer  undetected  by  man  than  would  otherwise 
have  been  the  case.  Something  of  the  same  in- 
felicity of  appointment  defeats  the  making  of  their 
acquaintance  by  many  observers  to-day.  They  look 
at  the  wrong  time. 

New  method  From  their  changes  in  conspicuousness  it  was 
research-  evident  that  the  canals,  like  the  large  blue-green 
patches  on  the  disk,  were  seasonal  in  their  habit. 
To  discover  with  more  particularity  what  their  law 
of  change  might  be,  an  investigation  to  that  end 
was  conceived  and  undertaken  at  the  opposition  of 
1903,  and  in  consequence  a  singular  thing  was 
brought  to  light.  The  research  in  question  was  the 
determination  from  complete  drawings  of  the  disk 
of  the  varying  visibility  of  the  several  canals  statisti- 
cally considered  during  a  period  of  many  months. 


THE   CANALS   AND   OASES   OF  MARS    169 

For  the  making  of  the  drawings  extended  over  this 
time,  and  by  a  comparison  of  them  one  might  note 
how  any  particular  canal  had  altered  in  the  interval. 
Their  great  number  enabled  accidental  errors  to  be 
largely  eliminated,  and  so  assured  a  more  trustworthy 
result.  Systematic  conditions  affecting  visibility  — 
such  as  our  own  air,  the  position  of  the  marking, 
and  the  size  of  the  disk  —  were  allowed  for,  so  as 
to  make  the  drawings  strictly  comparable.  On  the 
average,  there  were  for  each  canal  TOO  drawings  in 
which  that  canal  either  appeared  or  might  have  done 
so.  And  as  109  canals  were  considered  in  all,  there 
resulted  10,900  separate  determinations  as  basis  for 
the  eventual  conclusion. 

The  object  now  was  to  adopt  some  procedure  by 
which  this  mass  of  material  might  be  made  to  yield 
statistical  information,  not  simply  qualitative  but 
quantitative  results.  Here  the  planet  itself  sug- 
gested a  way.  Owing  to  the  rotation  of  Mars  any 
region  would  be  carried  in  and  out  of  sight  to  an 
observer  in  space  once  in  24  hours  and  40  minutes. 
But  owing  to  an  analogous  rotation  of  the  earth 
the  observer  himself  is  not  always  in  a  position  to 
see.  Furthermore,  the  two  rotations  are  not  quite 
synchronous  and  are  besides  complicated  by  the 
motions  of  the  two  planets  in  their  orbits.  The 
result  is  that  there  takes  place  a  slow  falling  behind 


170      MARS   AS   THE  ABODE   OF   LIFE 

in  the  longitudes  of  Mars  presented  centrally  to  the 
earth  at  the  same  hour  on  successive  nights.  If  we 
could  only  see  the  planet  for  a  minute  each  night, 
we  should  think  it  to  be  slowly  rotating  backward 
at  the  rate  of  9.6'°  of  its  own  longitude  a  day.  In 
consequence  any  given  marking  can  only  be  well 
observed  for  about  a  fortnight  consecutively,  after 
which  it  passes  off  the  disk  at  the  hours  suitable 
for  observation,  not  to  return  again  for  a  month.  Its 
times  of  showing  are  called  presentations. 

Now  in  the  subject  we  are  considering  these 
presentations  mark  epochs  six  weeks  apart  at  which 
the  state  of  any  marking  may  be  examined  in  all 
the  drawings  in  which  it  might  then  appear,  a  per- 
centage of  visibility  deduced  for  it  and  then  the 
percentages  for  its  several  successive  presentations 
compared. 

By  this  method  results  may  be  got  of  quantita- 
tive value,  capable  of  approaching  something  like 
exactitude  from  being  each  the  mean  of  many 
observations,  and  observations  made  with  an  eye  to 
no  specific  outcome  —  indeed,  incapable  of  being  so 
adapted  in  advance  as  the  result  showed. 

It  is  pleasing  to  note  that  to  no  one  has  the 
method  commended  itself  more  than  to  Schiaparelli. 
To  welcome  new  procedures  is  the  test  of  great- 
ness, for  it  betokens  breadth  of  view.  Most  men's 


THE   CANALS  AND   OASES   OF   MARS    171 

knowledge  is  cut  on  a  bias  of  early  acquisition,  and 
cannot  be  adapted  to  new  habits  of  thought. 

The  percentages  of  visibility  of  the  109  canals  at 
each  of  their  presentations  having  thus  been  obtained, 
a  tabulation  of  them  showed  what  had  been  each 
canal's  history  during  the  period  it  was  under  obser- 
vation. From  perusal  of  the  table  could  be  learned 
the  canal's  career,  whether  it  had  been  a  mere  un- 
changing line  upon  the  planet's  disk,  or  whether  for 
reason  peculiar  to  itself  it  had  varied  during  the 
interval.  To  show  this  the  more  easily,  the  per- 
centages were  plotted  upon  coordinate  paper,  in 
which  the  horizontal  direction  should  represent  the 
time  and  the  vertical  the  amount  of  the  percentage. 
Then  the  points  so  found  could  be  joined  by  a 
smooth  curve,  and  the  curve  would  instantly  ac- 
quaint the  eye  with  the  vicissitudes  of  the  canal's 
career  from  start  to  finish.  The  curve,  in  fact, 
would  be  its  history  graphically  represented,  and 
furthermore,  would  furnish  a  sign-manual  by  which 
it  might  be  specifically  known.  The  curve  could  be 
considered  the  canal's  cartouche,  —  after  the  manner 
of  the  ideographs  of  the  Egyptian  kings,  —  sym- 
bolizing its  achievements  and  distinguishing  it  at  once 
from  others. 

Since  the  height  of  the  curve  from  the  horizontal 
base  to  which  it  stood  referred  denoted  the  degree  of 


172      MARS   AS   THE   ABODE  OF   LIFE 

visibility  of  the  canal  at  the  moment,  any  deviation  in 
this  height  along  the  course  of  the  curve  showed  that 
the  canal  was  then  changing  in  conspicuousness  from 
intrinsic  cause.  If  the  height  grew  greater,  the  canal 
was  on  the  increase ;  if  less,  it  was  on  the  decline. 
For  precautions  had  already  been  taken  to  eliminate 
every  circumstance,  it  will  be  remembered,  which 
could  affect  the  canal's  appearance,  except  change  in 
the  canal  itself. 

Not  only  increase  or  decrease  in  the  canal  stood 
forth  thus  manifestly  confessed,  but  any  change  in 
the  rate  of  such  wax  and  wane  also  lay  revealed. 
In  looking  at  them,  one  has  only  to  remember  that 
the  action  proceeds  from  left  to  right  and  that  the 
ups  and  downs  of  the  curve  show  exactly  what  that 
action  was. 

Only  one  possible  form  out  of  them  all  indicates 
that  no  action  at  all  was  going  on  —  the  straight 
horizontal  line.  That  cartouche  signifies  that  its 
canal  was  a  dead,  inert,  unchanging  phenomenon  for 
the  period  during  which  it  was  observed. 

Now,  of  all  the  109  canals  examined,  only  three 
cartouches  came  out  as  horizontal  straight  lines,  and 
even  these  it  is  possible  to  doubt.  This  is  a  most 
telling  bit  of  information.  To  begin  with,  it  is  an 
obiter  dictum  of  the  most  subtly  emphatic  sort  upon 
the  reality  of  the  canals.  It  states  that  the  canals 


AT  THE  TELESCOPE 
Experiments  in  Artificial  Disks. 


THE   CANALS   AND   OASES   OF   MARS    173 

cannot  be  optical  or  illusory  phenomena  of  any  kind 
whatsoever  without  in  the  least  going  out  of  its  way 
to  do  so,  as  a  judge  might  lay  down  some  quite 
indisputable  point  of  law  in  the  course  of  a  more 
particular  charging  of  the  jury.  For  an  illusion 
could  no  more  exhibit  intrinsic  change  than  a  ghost 
could  eat  dinner  without  endangering  its  constitution. 
The  mere  fact  that  it  is  an  illusion  or  optical  product 
renders  it  incapable  of  spontaneous  variation.  Con- 
sequently, its  cartouche  would  be  a  horizontal  straight 
line.  As  the  cartouches  are  not  such  lines,  we  have 
in  them  instant  disproof  of  optical  or  illusory  effects 
of  every  kind. 

Now,  that  the  cartouches  are  curves  shows  that 
the  action  in  them  is  not  uniform,  but  increases  or 
decreases  more  at  one  season  than  at  another. 
Furthermore,  as  the  curves  both  rise  and  fall  in  the 
course  of  their  career,  the  action  they  typify  must 
consist  of  alternate  wax  and  wane.  It  is,  therefore, 
periodic,  which  leads  us  again  to  the  fact  that  it  is 
seasonal. 

Thus,  to  take  the  canal  Ceraunius,  we  note  that 
it  dwindled  from  the  time  it  was  first  observed,  June  5 
in  the  Martian  calendar,  till  about  the  end  of  June. 
It  then  started  to  increase  in  conspicuousness  intrin- 
sically, in  short  to  grow,  until  the  early  part  of 
August,  subsequently  to  which  it  again  declined, 


174      MARS  AS   THE  ABODE   OF   LIFE 

vanishing  after  the  first  frost.  Its  cartouche  further 
shows  that  its  waning  was  a  slow  process  of  extinc- 
tion, its  wax  a  relatively  sudden  one. 

Search  for  clew  From  the  knowledge  about  the  individual  canal 
which  the  cartouches  thus  afford,  we  advance  to  what 
they  prove  capable  of  imparting  by  collective  coor- 
dination with  one  another.  To  compare  them  it 
was  necessary  to  select  some  point  of  the  cartouche 


Days  before       S^USTT  K^E                                                Days  after                               FROST 
-30                     o                   jo                    60                   fo                   izo  \                iy> 

laf^fN 
CerauniutN 

Mean  Long.  74- 

*/ 

s#  

©-—  ». 

•^ 

j.^ 

La  1.75-N 

CARTOUCHE  OF  THE  CERAUNIUS 

From  a  chart  made  by  Professor  Lowell. 

adapted  to  comparison  purposes.  The  one  that  sug- 
gested itself  was  the  point  where  the  curve  fell  to 
a  minimum.  This  point  denoted  the  time  at  which 
each  canal  began  to  increase  in  conspicuousness,  the 
dead  point  from  which  it  rose.  This  dead  point 
was  found  for  each  cartouche,  and  starred  on  the 
curve.  When  this  had  been  done  and  the  cartouches 
tabled,  at  a  first  glance  it  seemed  as  if  comparison 
were  hopeless  for  the  detection  of  any  underlying 
principle  and  each  cartouche  only  a  law  unto  itself. 
But  by  recalling  that  the  canals  exist  upon  the 
surface  of  a  globe  and  that  the  two  directions  for 


THE   CANALS  AND   OASES   OF   MARS    175 

positioning  a  place  upon  a  sphere  are  longitude  and 
latitude,  we  are  led  to  try  latitude  as  the  more 
promising  of  the  two  to  furnish  a  clew. 

To  this  end  the  canals  were  segregated  according 
to  the  zone  on  the  planet  in  which  they  lay,  and 
their  separate  values  for  consecutive  times  combined 
into  a  mean  canal  cartouche  for  the  zone.  This 
was  done  for  all  the  zones,  and  the  mean  cartouches 
were  then  placed  in  a  column  descending  according 
to  latitude. 

The    result    was    striking.      Following    down    the  Quickening  of 
column,  there  is  evident    a    delay    in    the    time    of  .canals  a(xord~ 

•  ing  to  latitude. 

occurrence  of  the  minimum  as  we  descend  the 
latitudes.  This  means  that  the  canals  started  to  in- 
crease from  their  dead  point  at  successively  later 
epochs  in  proportion  to  their  distance  from  the 
planet's  polar  cap. 

Now,  before  seeking  to  put  this  symbolism  into 
comprehensive  terms,  —  to  do  which,  I  may  add 
^parenthetically,  is  just  as  scientific  and  far  more 
philosophic  than  to  leave  the  diagram  as  a  cryptic 
monument  of  a  remarkable  law,  which  it  were 
scientifically  impious  to  interpret,  —  another  fact  ex- 
hibited by  the  diagram  deserves  to  be  brought  out. 
It  appears,  if  attention  be  directed  to  it,  that  in  all 
the  mean  canal  cartouches,  the  gradient  is  less  be- 
fore the  minimum  than  after  it.  What  we  saw  to 


176      MARS   AS   THE   ABODE   OF   LIFE 

occur  in  the  Ceraunius  is  the  expression  of  a  general 
law  governing  the  canals.  The  curves  fall  slowly 
to  their  lowest  points,  and  rise  sharply  from  them. 
What  this  betokens  will  suggest  itself  on  a  moment's 
thought.  It  means  that  the  effects  of  a  previous 
motive  force  were  slowly  dying  out  in  the  first  part 
of  the  curves,  and  then  a  fresh  impulse  started 
in  to  act.  The  new  impulse  was  more  instant 
and  of  greater  strength  in  its  action,  and  by  piec- 
ing the  two  parts  of  the  curve  together,  we  con- 
clude that  it  was  in  both  cases  an  impulse  which 
acted  fairly  quickly  and  of  which  the  effects  took  a 
longer  time  to  die  out.  The  mean  cartouches,  then, 
assure  us  of  two  quickenings  and  lead  us  to  infer 
that  both  were  of  the  nature  of  forces  speedily  ap- 
plied and  then  withdrawn. 

Quickening  /  To  interpret  now  the  successive  growth  of  the 
°y  canals  latitudinally  down  the  disk  is  our  next  con- 
cern. We  saw  that  it  started  at  the  edges  of  the 
polar  cap.  Now,  such  an  origin  in  place  at  once 
suggests  an  origin  of  causation  as  well,  and  further- 
more precludes  all  other.  For  the  origin  of  time 
was  after  the  melting  of  the  cap.  First  the  cap 
melted,  and  then  the  canals  began  to  appear.  Those 
nearest  to  the  cap  did  so  first,  and  then  the  others 
in  their  order  of  distance  from  it,  progressing  in  a 
stately  march  down  over  the  face  of  the  disk. 


THE   CANALS  AND   OASES   OF   MARS    177 

Thus  we  reach  the  deduction  that  water  liberated 
from  the  polar  cap  and  thence  carried  down  the  disk 
in  regular  progression  is  the  cause  of  the  latitudinal 
quickening  of  the  canals.  A  certain  delay  in  the 
action,  together  with  the  amount  of  darkening  that 
takes  place,  seems  to  negative  the  supposition  that 
what  we  see  is  the  water  itself. 

On  the  other  hand,  vegetation  would  respond  only 
after  a  lapse  of  time  necessary  for  it  to  sprout,  —  a 
period  of,  say,  two  weeks,  —  and  such  tarrying  would 
account  for  the  observed  delay. 

Vegetation,  then,  explains  the  behavior  of  the 
canals.  Not  transference  of  water  merely,  but  trans- 
formation consequent  upon  transference,  furnishes 
the  key  to  the  meaning  of  the  cartouches.  Not 
the  body  of  water,  but  the  quickened  spirit  to  which 
it  gives  rise,  produces  the  result  we  see.  Set  free 
from  its  winter  storage  by  the  unlocking  of  the 
bonds  of  its  solid  state,  the  water,  accumulated  as 
jsnow,  begins  to  flow  and  starts  vegetation,  which 
becomes  responsible  for  the  increased  visibility  of  the 
canals.  / 

Waked  in  this  manner,  the  vegetal  quickening, 
following  the  water  with  equal  step,  but  only  after 
due  delay,  passes  down  the  disk,  giving  rise  to  those 
resuscitations  we  mark  through  the  telescope,  and 
attribute  not  without  reason  to  seasonal  change. 


178      MARS   AS   THE  ABODE   OF   LIFE 

Change  it  is,  and  seasonal  as  well,  yet  it  is  not  what 
we  know  by  the  name  in  one  important  particular. 
For  it  is  a  vernal  quickening  peculiar  to  Mars  which 
knows  no  counterpart  on  earth. 

The  earth  as         To  realize  this,  we    must    try  to  see  ourselves  as 
from  others  might  see.  us.     If  we  could  do  away  with  the 

cloud-envelope  which  must  to  a  great  extent  shield 
our  earth's  domestic  matters  from  prying  astronomers 
upon  other  orbs,  and  selecting  some  coign  of  vantage, 
as,  for  example,  Venus,  scan  the  face  of  our  familiar 
abode  from  a  distance  sufficient  to  merge  the  local 
in  the  general  aspect,  we  should  at  intervals  of  six 
months  notice  a  most  interesting  and  beautiful  trans- 
formation spread  over  it.  It  is  the  vernal  flush  of 
the  earth's  awakening  from  its  winter's  sleep  that  we 
should  then  perceive.  Starting  from  near  the  line 
of  the  tropic,  we  should  mark  the  surface  turn 
slowly  virescent.  As  the  tint  deepened,  we  should 
see  it  also  spread,  creeping  gradually  up  the  latitudes 
until  it  stood  within  the  Arctic  Circle  and  actually 
bordered  the  perpetual  snow. 

We  should  witness  thus  on  the  earth  much  what 
we  mark  on  Mars  at  intervals  twice  as  long,  because 
there  timed  to  the  greater  length  of  the  Martian 
year.  But  one  striking  difference  would  be  patent 
to  the  observer's  eye  :  on  earth  the  wave  of 
wakening  would  travel  from  equator  to  pole ;  on 


THE   CANALS   AND   OASES   OF 'MARS    179 

Mars  it  journeys  from  pole  to  equator.  So  much 
alike  in  their  general  detail,  the  two  would  thus  be 
parted  by  the  opposite  sense  of  the  action  to  a  di- 
versity which  at  first  would  seem  to  deny  any  like- 
ness in  cause.  To  us  the  very  meaning  of  .seasonal 
change  hinges  on  the  return  of  the  sun  due  to  our 
change  of  aspect  toward  it.  That  the  reverse  could 
by  any  reason  be  ascribed  to  the  same  means  might 
appear  at  first  impossible. 

Not  so  when  we  consider  it  with  care.  Apart 
from  the  all-important  matter  of  the  seed,  two  fac- 
tors are  concerned  in  the  vegetal  process,  the  absence 
of  either  of  which  is  equally  fatal  to  the  result.  The 
raw  material,  represented  by  oxygen,  nitrogen,  a  few 
salts,  and  water,  is  one  of  these ;  the  sun's  rays 
constitute  the  other.  Unless  it  be  called  by  the  sun, 
vegetation  never  wakes.  But,  furthermore,  unless  it 
have  water,  it  remains  deaf  to  the  call.  Now,  on 
the  earth  water  is,  except  in  deserts,  omnipresent. 
The  sun,  on  the  other  hand,  is  not  always  there. 
After  its  departure  south  in  the  autumn,  vegetation 
must  wait  until  its  return  in  the  spring. 

Mars  is  otherwise  circumstanced.     Dependent  like  Melting  first 
us  upon  the  periodic  presence  of  the  sun  directly,  it  ™^s 
is  further  dependent  upon  the  same  source  indirectly 
for  its  water-supply.     Not  having  any  surface  water 
except  such  as  comes  from  the  annual  unlocking  of 


i8o      MARS   AS   THE   ABODE   OF   LIFE 

the  snows   of  the    polar   cap,  vegetation    must    wait 
upon  this  unlocking  before    it    can   begin  to  sprout. 


SPROUTING  TIMES  OF  VEGETATION  ON  THE  EARTH 

The  earth  is  represented  upside  down,  in  direct  comparison  with  Mars  as  we  see 
it  in  the  telescope. 

From  a  chart  made  by  Professor  Lowell. 

The  sun  must  have  already  gone  north   and  melted 
the  polar  snows  before  vegetation    starts,  and    when 


THE   CANALS   AND   OASES   OF    MARS    181 

it  starts,  it  must  do  so  at  the  north,  where  the  water 
arises,  and  then  follow  the  frugal  flood  down  the 
disk.  Thus,  if  it  is  to  traverse  the  surface  at  all 
with  vegetation  in  its  train,  the  showing  must  begin 
at  the  pole  and  travel  to  the  equator. 

This,  to  us,  inverse  manner  of  vernal  progression 
is  precisely  what  the  cartouches  exhibit.  Their  curves 
of  visibility  show  that  the  verdure  wave  is  timed 
not  primarily  to  the  simple  return  of  the  sun,  but 
to  the  subsequent  advent  of  the  water,  and  follows, 
not  the  former  up  the  parallels,  but  the  latter  down 
the  disk. 

It  is  possible  to  gauge  the  speed  of  the  latitudi-  Speed  of 
nal  sprouting  of  the  vegetation,  and  therefore  of  the 
advent  of  the  water  down  the  canals,  by  the  differ- 
ence in  time  between  the  successive  darkenings  of 
the  canals  of  the  several  zones.  Thus  it  appears 
that  it  takes  the  water  fifty-two  days  to  descend 
from  latitude  72°  N.  to  the  equator,  a  distance 
0^2650  miles.  This  means  a  speed  of  51  miles 
a  day,  or  2.1  miles  per  hour. 

So,  from  our  study,  it  appears  that  a  definite  law 
governs  the  wax  and  wane  of  these  strange  things. 
Quickened  by  the  water  let  loose  on  the  melting  of 
the  polar  cap,  they  rise  rapidly  to  prominence,  to 
stay  so  for  some  months,  and  then  slowly  proceed 
to  die  out  again.  Each  in  turn  is  thus  affected,  the 


1 82      MARS   AS   THE   ABODE   OF   LIFE 

march  of  vivification  stalking  the  latitudes  with  steady 
stride  down  the  surface  of  the  disk.     Nothing  stops 

FT " 


SPROUTING  TIMES  OF  VEGETATION  ON  MARS 

From  a  chart  made  by  Professor  Lowell. 

its  measured  progress,  or  proves  deterrent  to  its 
course.  One  after  the  other  each  zone  in  order  is 
reached  and  traversed,  till  even  the  equator  is  crossed, 


THE   CANALS   AND   OASES   OF   MARS    183 

and  the  advance  invades  the  territory  of  the  other 
side.  Following  in  its  steps  afar,  comes  its  slower 
wane.  But  already,  from  the  other  cap,  has  started 
an  impulse  of  like  character  that  sweeps  reversely 
back  again,  travelling  northward  as  the  first  went 
south.  Twice  each  Martian  year  is  the  main  body 
of  the  planet  traversed  by  these  antistrophic  waves 
of  vegetal  awakening,  grandly  oblivious  to  everything 
but  their  own  advance.  Two  seasons  of  growth  it 
therefore  has,  one  coming  from  its  arctic,  one  from 
its  antarctic,  zone,  its  equator  standing  curiously  be- 
holden semestrally  to  its  poles.18 

There  is  something  stirring  to  thought  in  this 
solidarity  of  movement,  timed  in  cadence  to  the 
passage  of  the  year.  Silent  as  it  is,  the  eye  seems 
half  to  catch  the  measured  tread  of  its  advance  as 
the  darkening  of  the  canals  sweeps  on  in  progressive 
unison  of  march.  That  it  means  life,  not  death,  de- 
tracts no  jot  from  the  moving  quality  of  its  effect. 
For  all  its  peaceful  purpose,  the  rhythmic  majesty 
of  the  action  imposes  a  sense  of  power  on  the  mind, 
seeming  in  some  better  way  to  justify  the  planet's 
name  in  its  wholly  Martian  character.  Called  after 
the  god  of  war,  the  globe  is  true  to  its  character  in 
the  orderly  precision  of  its  stately  processional  change. 


CHAPTER   VI 

PROOFS    OF    LIFE    ON    MARS 

A  STRONOMICAL  discovery  is  of  two  kinds.  If 
•*-  ^-  it  consist  simply  in  adding  another  asteroid  or 
satellite  to  those  already  listed,  obedience  to  the  law  of 
gravitation,  with  subsequent  corroboration  of  place, 
alone  is  needed  for  belief.  But  if  it  relate  to  the  detec- 
tion of  an  underlying  truth  as  yet  unrecognized,  then 
it  is  only  to  be  unearthed  by  reasoning  on  facts  after 
they  are  obtained,  and  effects  credence  according  to 
one's  capacity  for  weighing  evidence.  Breadth  of  mind 
must  match  breadth  of  subject.  For  to  plodders  along 
prescribed  paths  a  far  view  fails  of  appeal ;  conserva- 
tive settlers  in  a  land  differ  in  quality  from  pioneers. 

Discovery  of  a  truth  in  the  heavens  varies  in 
nothing,  except  the  subject,  from  discovery  of  a  crime 
on  earth.  The  forcing  of  the  secrets  of  the  sky  is, 
like  the  forcing  of  man's,  simply  a  piece  of  detective 
work.  It  is  the  finding  of  a  cause  in  place  of  a  cul- 
prit ;  but  the  process  is  quite  similar.  Causa  criminis 
and  causa  discriminis  differ  only  by  a  syllable. 

Like,  too,  are,  or  should  be,  the  methods  em- 
184 


PROOFS   OF   LIFE   ON   MARS  185 

ployed.  In  astronomy,  as  in  criminal  investigation, 
two  kinds  of  testimony  require  to  be  secured.  Cir- 
cumstantial evidence  must  first  be  marshalled,  and  then 
a  motive  must  be  found.  To  omit  the  purpose  as 
irrelevant,  and  rest  content  with  gathering  the  facts,  is 
really  as  inconclusive  a  procedure  in  science  as  in  law, 
and  rarely  ends  in  convincing,  any  more  than  in 
properly  convicting,  anybody.  For  motive  is  just  as 
all-pervading  a  preliminary  to  cosmic  as  to  human 
events,  only  for  lack  of  fully  comprehending  it  we  call 
the  one  a  motive  and  the  other  a  cause.  Unless  we 
can  succeed  in  assigning  a  sufficient  reason  for  a  given 
set  of  observed  phenomena,  we  have,  not  greatly  fur- 
thered the  ends  of  knowledge  and  have  done  no  more 
than  the  clerkage  of  science.  A  theory  is  just  as 
necessary  to  give  a  working  value  to  any  body  of  facts 
as  a  backbone  is  to  higher  animal  locomotion.  It 
affords  the  data  vertebrate  support,  fitting  them  for 
the  pursuit  of  what  had  otherwise  eluded  search. 

"Coordination  is  the  end  of  science,  the  aim  of  all 
attempt  at  learning  what  this  universe  may  mean. 
And  coordination  is  only  another  name  for  theory,  as 
the  law  of  gravitation  witnesses.  Now,  to  be  valid,  a 
theory  must  fulfil  two  conditions :  it  must  not  be  con- 
tradicted by  any  fact  within  its  purview,  and  it  must 
assign  an  underlying  thread  of  reason  to  explain  all 
the  phenomena  observed.  Circumstantial  evidence 


1 86      MARS   AS   THE  ABODE   OF   LIFE 

must    first    lead    to    a  suspect,  and  then  this  suspect 
must  prove  equal  to  accounting  for  the  facts. 

This  method  we  shall  pursue  in  the  case  before  us ; 
and  it  will  conduce  to  understanding  of  the  evidence 
to  keep  its  order  of  presentation  to  the  detective  in 
presenting  it  at  the  bar  of  reason. 

Review  of  the  Starting  with  the  known  physical  laws  applicable  to 
'  ^e  concentration  of  matter,  we  found  that  though  in 
general  the  course  of  evolution  of  the  earth  and  Mars 
was  similar,  the  smaller  mass  of  Mars  should  have 
caused  it  to  differ  eventually  from  the  earth  in  some 
important  respects. 

Three  of  these  are  noteworthy:  (i)  its  surface 
should  be  smoother  than  the  earth's,  (2)  its  oceans 
relatively  less,  (3)  its  air  scantier.  On  turning  to  Mars 
itself  we  then  saw  that  these  three  attributes  of  the 
jplanet  were  precisely  those  the  telescope  disclosed, 
/(i)  The  planet's  surface  was  singularly  flat,  being 
| quite  devoid  of  mountains;  (2)  its  oceans  in  the  past 
covered  at  most  three-eighths  of  its  surface  instead  of 
three-quarters,  as  with  us  ;  (3)  its  air  was  relatively 
thin. 

Aspect  of  We    next    showed  that  physical    loss  should,  from 

are  con-o     ij^  smaller  mass,  have  caused  it  to  age  quicker,  and 

rates  principles   ; 

of  planetary     that  this  aging  should  reveal  itself  by  the  more  com- 

evolution.  -        .  .  .  . 

plete  departure  or  what  oceans  it  once  possessed  and 
by  the  wider  spread  of  deserts. 


PROOFS   OF   LIFE   ON   MARS          187 

Telescopic  observation  we  then  found  asserted  these 
two  peculiarities:  (i)  no  oceans  now  exist  on  the 
planet's  surface ;  (2)  desert  occupies  five-eighths  of  it. 

From  such  confirmation  of  the  principles  of  planet- 
ary evolution  from  the  present  aspect  of  the  planet 
Mars,  we  went  on  to  consider  the  two  most  essen- 
tial prerequisites  to  habitability :  water  and  warmth. 
Water  we  sought  first ;  and  we  found  it  in  the  polar 
caps.  The  phenomena  of  the  polar  caps  proved  ex- 
plicable as  consisting  of  water,  and  not  as  of  anything 
else.  Still  more  important  was  the  question  of  tem- 
perature. We  took  this  up  with  particularity.  We 
found  several  factors  to  the  problem  not  hitherto 
reckoned  with,  and  that  when  these  were  taken  into 
account  the  result  came  out  entirely  different  from 
what  had  previously  been  supposed.  Instead  of  a 
temperature  prohibitive  to  life,  one  emerged  from  our 
research  entirely  suitable  for  it.  And  this  even  more 
for  animals  than  plants.  For  a  climate  of  extremes 
was  what  that  of  Mars  appeared  to  be,  with  the 
summers  warm.  Now,  investigations  on  earth  have 
shown  that  it  is  the  temperature  of  the  hottest  season 
that  determines  the  existence  of  animals,  cold  much 
more  adversely  affecting  plants.  Yet  to  the  presence 
of  the  latter  the  loo*k  of  the  disk  conformed.  Scan- 
ning it,  we  marked  effects  which  could  only  be  ex- 
plained as  vegetation.  Thus  the  conditions  on  Mars 


1 88      MARS   AS   THE   ABODE   OF   LIFE 

showed  themselves  hospitable  to  both  great  orders  of 
life,  the    latter    actually  revealing    its  presence  by  its 
seasonal  changes  of  tint. 
Animal  life          Here  we  reached  the  end  of  what  might  directly  be 

disclosed  only       ......  .  r      i  i  T-< 

b  mind  disclosed  in  the  organic  economy  or  the  planet,  ror 
at  this  point  we  brought  up  before  a  most  significant 
fact:  that  vegetable  life  could  thus  reveal  itself  directly, 
but  that  animal  life  could  not.  Not  by  its  body,  but 
by  its  mind,  would  it  be  known.  Across  the  gulf  of 
space  it  could  be  recognized  only  by  the  imprint 
it  had  made  on  the  face  of  Mars. 

Canals  con-  /  Turning  to  the  planet,  we  witnessed  a  surprising 
thing.  There  on  the  Martian  disk  were  just  such 
markings  as  intelligence  might  have  made.  Seen  even 
with  the  unthinking  eye,  they  appear  strange  beyond 
belief,  but  viewed  thus,  in  the  light  of  deduction,  they 
seem  positively  startling,  like  a  prophecy  come  true. 

Confronting  the  observer  are  lines  and  spots  that 
but  impress  him  the  more,  as  his  study  goes  on,  with 
their  non-natural  look.  So  uncommonly  regular  are 
they,  and  on  such  a  scale,  as  to  raise  suspicion  whether 
they  can  be  by  nature  regularly  produced.  Next  to 
one's  own  eyesight  the  best  proof  of  this  is  the  un- 
solicited indorsement  it  has  received  in  the  scepticism 
their  depiction  invariably  evokes.  Those  who  have 
not  been  privileged  to  see  them  find  it  well-nigh  im- 
possible to  believe  that  such  things  can  be.  Nor  is 


PROOFS   OF   LIFE   ON   MARS          189 

this  in  the  least  surprising.  But  however  consonant 
with  nescience  to  doubt  the  existence  of  the  lines  on 
this  score,  to  do  so  commits  it  to  witness  against  itself 
of  the  most  damaging  character  the  moment  their  exist- 
ence is  proved.  Now,  assurance  of  actuality  no  longer 
needs  defence.  The  lines  have  not  only  been  amply 
proved  to  exist,  but  have  actually  been  photographed, 
and  doubt  has  shifted  its  ground  from  existence  to 
character,  a  half  retreat  tantamount  to  a  complete  sur- 
render. For  without  equal  investigation,  to  admit  a 
discovery  and  deny  its  description  is  like  voting  for  a 
bill  and  against  its  appropriation.  It  reminds  one  of 
the  advice  of  the  old  lawyer  to  a  junior  counsel : 
"  When  you  have  no  case,  abuse  the  plaintiff's 
attorney." 

Unnatural  regularity,  the  observations  showed, 
betrays  itself  in  everything  to  do  with  the  lines  :  in 
their  surprising  straightness,  their  amazing  uniformity 
throughout,  their  exceeding  tenuity,  and  their  im- 
mense length.  These  traits,  instead  of  disappearing, 
the  better  the  canals  have  been  seen,  as  was  confidently 
prophesied,  have  only  come  out  with  greater  insistence. 
With  increased  study  not  only  the  assurance  gains  that 
they  are  as  described,  but  a  mass  of  detail  has  been 
added  about  them  impossible  to  reconcile  with  any 
natural  known  process. 

A  single  instance  of  the   methodism  that  confronts 


i9o      MARS   AS   THE   ABODE   OF   LIFE 


us  will  serve  to  make  this  plain.  The  Lucus  Ismenius 
is  a  case  in  point.  The  marking  so  called  consists  of 
two  round  spots  each  about  seventy-five  miles  in 

diameter.  They  lie  close 
together,  not  more  than 
fifty  miles  of  ochre  ground 
parting  their  peripheries. 
Into  them  converge  a 
number  of  canals — seven 
doubles  and  five  singles. 
Now,  the  manner  of  these 
meetings  is  curiously  de- 

LUCI    ISMENII,   REVEALING   THE   SYS-      tailed.         TllTCC        of      the 

TEMATIC  METHOD  IN  WHICH  THE 

DOUBLE  CANALS  ENTER  THE  TWIN    doubles  embrace  the  oases, 

just  enclosing  them  be- 
tween their  two  arms.  The 
four  other  doubles  send  a 
line  to  each  oasis  to  enter 
it  centrally.  Which  con- 
nection the  double  shall 
adopt  apparently  depends 
upon  the  angle  at  which 

the  approach  is  made.  If  the  direction  be  nearly 
vertical  to  the  line  of  the  two  oases,  the  entrance 
is  central ;  if  parallel,  it  is  an  embrace.  As  for  the 
singles,  they  connect  with  one  or  the  other  oasis, 
as  the  case  may  be.  Such  precise  and  methodical 


1.  Euphrates,  double. 

2.  Hiddekel,  double. 

3.  Protonilus,  double. 

4.  Deuteronilus,  double. 

5.  Astaboras,  double. 

6.  Djihoun,  double. 

7.  Arnon,  convergent  double. 

8.  Aroeris.  9.  Sados. 
10.   Pallacopas.              n.   Phthuth. 

12.  Naarmalcha,  double. 

13.  Naarsares. 


PROOFS   OF   LIFE   ON   MARS 


191 


arrangement,  thus  marvellously  articulated  and  de- 
tailed, discloses  an  orderliness  so  surprising,  if  on 
nature's  part,  as  to  throw  us  at  once  into  the  arms  of 
the  alternative  as  the  least  astonishing  of  the  two. 

Before  passing  on  Not  rivers, 

to  reason  upon  the 
fact,  we  note  that 
the  characters  men- 
tioned are  them- 
selves enough  to 
negative  all  sup- 
positions of  natural 
cause.  First,  the 
lines  cannot  be 
rivers,  since  rivers 
are  never  straight 
and  never  uniform 
in  width.  Now,  we 
see  the  canals  so 
well  as  to  be  quite 
certain  of  their  even- 
ness. The  best  proof  of  this  is  that,  though  each  is 
uniform,  some  are  at  least  ten  times  the  size  of  others. 
If  one  of  them  dwindled  en  route,  we  should  have 
ample  measure  of  the  fact. 

Nor  can  the  lines  be  cracks  in  the  surface,  because  Not  cracks. 
cracks  also  are  not  straight,  and  because  cracks  end 


From  a  drawing  by  Professor  Lov 

THE  MOON,  SHOWING  THE  STRAIGHT  WALL 

AND    RlLL   TO   THE   RIGHT   OF  BlRT,  MAY, 
1905 

These  are  palpable  cracks  like  those  in  a  ceiling, 
and  quite  unlike  the  uniform  canal  lines  of 
Mars. 


192      MARS   AS   THE   ABODE   OF   LIFE 

before  finishing.  We  have  examples  of  undoubted 
cracks  in  more  than  one  heavenly  body,  and  their 
appearance  is  quite  unlike  the  look  of  the  lines  of 
Mars.  The  moon  offers  such  in  many,  if  not  all,  of 
her  so-called  rills. 

To  the  most  superficial  view  these  suggest  their 
nature,  but  when  carefully  examined  at  Flagstaff, 
corroboration  of  the  fact  came  out  in  certain  definite 
characteristics.  For  the  rills  proved  to  be  made  of 
parts  which  overlapped  at  their  ends,  one  fractional 
line  taking  up  the  course  before  the  other  had  given 
out,  thus  exactly  reproducing  the  composition  of  the 
cracks  in  any  plaster  ceiling. 

Mercury  bears  testimony  to  the  same  effect.  Its 
lines,  more  difficult  than  the  canals  of  Mars,  —  for 
we  see  Mercury  four  times  as  far  off  when  best 
placed  as  we  do  Mars,  —  though  roughly  linear,  are 
not  unnatural  in  appearance  even  at  that  great  dis- 
tance, and  show  irregularities  suggestive  of  cracks. * 
In  the  markings  on  Venus,  too,  there  is  nothing 
unnatural. 

other  natural  Rivers  and  cracks  are  the  two  most  plausible  sup- 
"ovTiTos  positions  made  to  account  for  the  lines  on  any  theory 
sibie.  Of  natural  causation.  Other  guesses  have  been  in- 

*  Lately,  at  least  two  critics  have  stated  that  the  descriptions  of  the  spoke-like 
markings  seen  on  Venus  at  Flagstaff  in  1897  and  later,  are  inconsistent.  The  seeming 
inconsistency  is  due  to  our  own  air,  which  sometimes  defines  them,  sometimes  not. 
The  important  point  about  them  is  that  the  Venusian  lines  are  irregular.  —  P.  L. 


PROOFS   OF   LIFE   ON   MARS 


'93 


i94      MARS   AS   THE   ABODE   OF   LIFE 

dulged  in,  such  as  that  meteors  by  their  passing 
attraction  have  raised  the  lines  as  welts  upon  the 
surface  —  welts  easily  allayed  by  application  of  the 
fact  that  the  lines  change  with  the  seasons,  actually 
disappearing  at  certain  epochs,  to  revive  again  at 
others.  Such  suggestions  there  are,  but  none  have 
been  advanced  to  my  knowledge  that  bear  the  most 
cursory  inspection. 

Still  more  inexplicable  on  any  natural  hypothesis 
is  the  systematized  arrangement  of  the  lines  to  form 
a  network  over  the  whole  planet.  That  the  lines 
should  go  directly  from  certain  points  to  certain 
others  in  an  absolutely  unswerving  direction ;  that 
they  should  there  meet  lines  that  have  come  with 
like  directness  from  quite  different  points  of  depar- 
ture ;  that  sometimes  more  than  ten  of  them  should 
thus  rendezvous,  and  rarely  less  than  six ;  and  that, 
lastly,  this  state  of  intercommunication  should  be 
true  all  over  the  disk,  are  phenomena  that  no  natural 
physical  process  that  I  can  conceive  of —  and  no 
one  else  seems  to  have  been  able  to,  either  —  can 
in  the  least  explain.  Yet  this  arrangement  cannot 
be  due  to  chance,  the  probabilities  against  the  lines 
meeting  one  another  in  this  orderly  manner  being 
millions  to  one. 

Oases  equally         But     the     canals    are    not  all    that   is   wonderful ; 

mexpiicabie.     we  jiave   to    reckon  w}th  the  oases    as    well.     These 


PROOFS   OF   LIFE   ON   MARS          195 

are  remarkable,  both  in  themselves  and  in  their  re- 
lation to  the  system  of  lines ;  for  they  occur  at  the 
junctions  —  only  at  the  junctions,  and  virtually  al- 
ways at  the  junctions.  They  are  thus  of  the  nature 
of  knots  to  the  network.  No  explanation  can  be 
given  of  this  by  purely  physical  laws. 

So  we  might  go  on,  with  the  enigma  of  the  double 
canals  more  and  more  mysterious  the  more  one  learns 
about    them  —  with 
their    strange    posi- 
tioning on  the  planet 

in  the  tropical  belts: 

•*"  -- >.  '  "*x..* ' 

with      the     curious  *"SJ^ 

phenomenon  of  con-  .* 

verging    or    wedge-  , 

shaped  doubles  de- 
scending     to     join 
them  from  the  pole  ; 
and  with  other  facts          A  CORNER  OF  MARS>  JUNE  I0>  ,90>J 
equally  odd. 

But  long  before  the  catalogue  of  geometric 
curiosities  had  drawn  to  its  close,  —  for  it  were 
wearisome  to  count  them  all,  and  where  even  one 
is  so  cogent,  numbers  do  not  add,  —  it  becomes 
apparent  to  any  one  capable  of  weighing  evidence 
that  these  things  which  so  palpably  imply  artificiality 
on  their  face  cannot  be  natural  products  at  all,  but 


196      MARS   AS   THE   ABODE   OF   LIFE 

that  the  observer  apparently  stands  confronted  with 
the  workings  of  an  intelligence  akin  to  and  there- 
fore appealing  to  his  own.  What  he  is  gazing  on 

typifies  not  the  out- 
come of  natural 
forces  of  an  ele- 
mental kind,  but  the 
artificial  product  of  a 

mind  directing  it  to 
ARETHUSA  Lucus,  APRIL  15,  1903,  SHOWING 

CONVERGING  CANALS  FROM  THE  NORTH      a  purposed  and  defi- 

POLAR  CAP  nite  end. 

When  once    this    standpoint  is  adopted,  we  begin 

to    see    light.     The    recognition    of  artificiality    puts 

us   on   a    track  where  we    gather    explanation    as   we 

proceed. 

Great-circle          Thus  two  attributes,  one  of  the  canals,  the    other 

character  of  c       1  r      J  1  T«I 

the  canals  °*  ^  oases>  ^n^  explanation  at  once.  The  great- 
circle  directness  of  the  lines  stands  instantly  inter- 
preted. On  a  sphere  a  great  circle  takes  the 
shortest  distance  between  two  points.  It  offers, 
therefore,  the  most  expeditious  route  from  one  place 
to  another.  It  is,  then,  that  which,  when  possible, 
intelligence  would  adopt.  Even  in  the  case  of  our 
very  accidented  earth,  our  lines  of  communication 
are  being  rectified  every  year  as  we  progress  in 
mastery  of  our  globe. 

Equally   suggestive    is    the    shape  of  the   oases,  or 


PROOFS   OF   LIFE   ON   MARS 


spots,  that  button  the  lines  together.  For  they  circularity 
show  round.  Now,  a  solid  circle  has  the  peculiar 
property  that  the  average  distance  from  its  centre 
to  all  points  in  it  is  less  than  for  any  figure  enclos- 
ing a  like  area.  It  would  be  the  part  of  intelli- 
gence, then,  to  construct  this  figure  whenever  the 
greatest  amount  of  ground  was  to  be  reached  for 
tillage  or  any  other  purpose  at  the  least  expendi- 
ture of  force. 

No  less  telltale  is  their  behavior ;  and  now  not 
only  of  the  bare  fact  of  artificiality,  but  of  the 
manner  in  which  it  came  to  be. 

The  extreme  threads  of  the  world-wide  network 
of  canals  stand  connected  with  the  dark-blue  patches 


CANALS  FROM  THE  SOUTH  POLAR 
CAP,  THE  WHITE  BONNET  AT 
THE   TOP    OF    THE    PICTURE, 
JUNE  6,  1907 
Martian  date,  September  22. 


CANALS  FROM  THE  SOUTH  POLAR 
CAP,  SHOWN  AT  THE  Top  OF 
THE  PICTURE,  OCTOBER  25, 
1907 

Martian  date,  December  18. 


at  the  edge  of  one  or  the  other  of  the  polar  caps. 
But  they  are  not  always  visible.  In  the  winter 
season  they  fail  to  show.  Not  till  the  cap  has 


198      MARS   AS   THE   ABODE   OF   LIFE 

begun  to  melt,  do  they  make  their  appearance,  and 
then  they  come  out  dark  and  strong.  Now,  the 
cap  in  winter  is  formed  of  snow  and  ice  that  melts 
as  summer  comes  on.  Here,  then,  the  attentive 
ear  seems  to  catch  the  note  of  running  water. 

From  their  poleward  origin  the  lines  begin  to 
darken  down  the  disk.  One  after  the  other  takes 
up  the  thread  of  visibility,  to  hand  it  on  to  the  next 
in  place.  So  the  strange  communication  travels, 
carried  from  the  arctic  zone  through  the  temperate 
and  the  tropic  ones  on  to  the  equator,  and  then  be- 
yond it  over  into  the  planet's  other  hemisphere.  A 
flow  is  here  apparent,  journeying  with  measured 
progress  over  the  surface  of  this  globe.  Here,  again, 
the  mental  ear  detects  the  sound  of  water  percolat- 
ing down  the  latitudes. 

Across  what  once  were  seas,  but  are  seas  no  more, 
the  darkening  of  the  lines  advances,  with  the  same 
forthrightness  as  over  the  ochre  continental  tracts. 
Blue-green  areas  of  vegetation  and  arid  wastes  alike 
are  threaded  by  the  silent  deepening  of  tint.  Lati- 
tude bars  it  not,  nor  character  of  country.  It 
great-circles  the  old  sea  bottoms  as  cheerfully  as  it 
caravans  the  desert  steppes.  This  persistency  made 
possible  by  the  loss  of  what  the  seas  once  held,  the 
thought  of  water  is  once  more  thrust  upon  the 
sense,  its  absence  now  as  telling  as  its  presence  was 


PROOFS   OF   LIFE   ON   MARS          199 

before.     One    hears  it  in  the   very  stillness  the  lack 
of  it  promotes. 

Then,  as  with  quickened  sense  one  listens,  the 
mind  is  aware  of  antiphonal  response  in  the  unlock- 
ing of  the  other  cap  to  send  its  scanty  hoardings 
in  similar  rilling  over  the  long-parched  land.  The 
note  of  water  confronts  us  thus  at  every  turn  of 
this  strange  action.  Water,  then,  must  be  the 
word  of  the  enigma :  the  clew  that  will  lead  us  to 
the  unloosening  of  the  riddle. 

But  though  water  it  be,  this  is  not  the  complete  its 
solution  of  the  problem ;  for,  as  one  ponders,  the 
unnatural  character  of  the  action  dawns  on  one. 
That  a  wave  of  progression  passes  through  the 
canals  down  the  disk ;  that  something,  then,  pro- 
ceeds from  the  pole  to  the  equator ;  and  that  this 
something  can  be  none  other  than  water,  giving  rise 
to  vegetation,  sounds  simple  and  forthright.  The 
startling  character  of  the  action  is  not  at  once 
apparent.  It  becomes  so  only  when  we  try  to 
account  for  the  locomotion.  When  we  so  envisage 
it,  the  transference  turns  out  to  be  a  most  astound- 
ing and  instructive  thing. 

To  understand  wherein  lies  its  peculiarity,  we  must 
consider  the  shape  of  the  planet.  For  the  planet  is 
flattened  at  the  poles  by  -^gir  °f  ^ts  diameter.  This,  to 
begin  with,  will  make  the  action  seem  even  stranger 


200      MARS   AS   THE   ABODE   OF   LIFE 

than  it  is.  It  might  seem  at  first  as  if  the  water  in 
going  to  the  equator  had  to  run  twenty-one  miles 
uphill. 

Mars'  sur&ce  If  Mars  did  not  rotate,  its  figure  would  be  a 
librium.  sphere,  except  for  such  tidal  deformation  as  outside 
bodies  might  give  it,  because  its  own  gravity  would 
pull  it  into  a  shape  similar  in  all  directions.  As 
Mars  rotates,  its  rotatory  momentum  bulges  it  at 
the  equator,  changing  the  sphere  into  what  is  called 
an  oblate  spheroid  of  the  general  form  of  an 
orange.  The  ellipticity  of  a  rotating  mass  is  affected 
not  only  by  the  size  of  the  body  and  by  the  speed 
of  rotation,  but  by  the  distribution  of  the  matter 
composing  it.  Thus  it  is  different  for  a  homo- 
geneous body  than  for  a  heterogeneous  one,  and 
differs  according  to  the  law  of  density  from  surface 
to  centre.  Now  it  is  an'  interesting  fact  that  the 
oblateness  of  Mars — j-g^y  found  by  two  indepen- 
dent methods  quite  independently  applied ;  one 
from  measurements  of  the  planet  made  in  1894  at 
Flagstaff  by  Mr.  Douglass,  reduced  and  discussed 
by  the  director ;  the  other  from  the  motions  of  the 
satellites  by  Hermann  Struve — should  fall  between 
the  value  it  would  have,  were  it  homogeneous,  and 
that  which  it  would  show  did  the  density  increase  from 
surface  to  centre  in  the  same  manner  as  on  earth. 
But  we  can  see  from  theory  that  it  should  lie  be- 


PROOFS   OF   LIFE   ON   MARS          201 

tween  these  two  extremes.  For  the  compression 
there  is  not  so  great  as  with  the  earth  because  of 
Mars'  smaller  mass.  In  this  we  find  another  proof, 
were  any  needed,  that  the  evolution  of  both  planets 
was  as  sketched  in  our  opening  chapter.  A  rapidly 
rotated  mass  of  putty  will  take  on  the  same  shape. 
In  the  case  of  Mars  the  stresses  are  so  enormous 
that  for  a  long  acting  force,  such  as  is  here  con- 
cerned, the  planet,  although  probably  as  rigid  as 
steel,  behaves  as  if  its  mass  were  plastic.  The 
result  is  that  the  direction  of  gravity  is  always  per- 
pendicular to  the  surface  at  every  point ;  or,  in 
other  words,  the  surface  is  in  stable  equilibrium. 

Now,    the    fact    that  every  point  of  the  surface  is  Gravity  m- 
in    equilibrium    means    that    any  particle    of  a  liquid  caPableof 
there  —  as,    for   example,    a   drop    of  water  —  would  ference. 
not    move,    but   would    stay    where  it  was.      For    all 
the    forces     being    exactly    balanced    to    rest,    their 
resultant    cannot    solicit    it   to    stir.     Just    as  on  the 
surface    of  the  earth,  water  upon    a    level  stretch  of 
ground  shows  no   tendency  to  move. 

Consequently,  any  water  set  free  near  the  pole 
by  the  melting  of  the  polar  cap  would  stay  where 
it  was  liberated  without  the  least  inclination  to  go 
elsewhere.  The  only  force  which  would  have  the 
slightest  effect  upon  it  might  be  its  own  head,  if  it 
had  any.  Were  the  melting  ice  or  snow  that  gave 


202      MARS   AS   THE   ABODE   OF   LIFE 

birth  to  it  ten  feet  thick,  and  it  is  more  likely  to  be 
less,  it  would  give  rise  to  an  average  head  of  water 
of  five  feet.  Now,  a  head  of  five  feet  could  not 
urge  the  water  against  surface  friction  more  than  a 
few  miles  at  most.  So  that  any  such  impulse  is 
quite  impotent  to  the  effects  we  see. 

Face  to  face,  then,  we  find  ourselves  with  a  mo- 
tion of  great  magnitude  occurring  without  visible  or 
physically  imaginable  cause.  A  body  of  water  travels 
3300  miles  at  the  rate  of  51  miles  a  day  under  no 
material  compulsion  whatever. 

It  leaves  the  neighborhood  of  the  pole,  where  it 
was  gravitationally  at  home,  and  wanders  to  the 
equator,  where  gravitationally  it  was  not  wanted, 
without  the  slightest  prompting  on  the  part  of  any 
natural  force.  The  deduction  is  inevitable ;  it  must 
have  been  artificially  conducted  over  the  face  of  the 
planet.  We  are  left  no  alternative  but  to  suppose 
it  intelligently  carried  to  its  end. 

Nor  is  this  the  limit  of  the  extraordinary  per- 
formances shown  by  the  progressive  darkening  of 
the  canals  down  the  disk.  Were  they  actuated  by 
natural  forces,  what  they  next  do  would  be  simply 
incredible.  For,  not  content  with  descending  to  the 
equator  without  visible  means  of  propulsion,  once 
arrived  there,  they  promptly  proceed  to  cross  it  into 
the  planet's  other  hemisphere  and  run  up  the  lati- 


PROOFS   OF   LIFE   ON   MARS          203 

tudes  with  equal  celerity  on  the  other  side.  Now, 
any  physical  inducement  given  them  to  come  equa- 
torward  must  have  its  action  reversed  so  soon  as 
that  dividing-line  was  crossed.  If,  then,  they  were 
in  any  way  helped  to  the  earlier  part  of  their  pere- 
grination by  natural 
forces,  they  would  be 
hindered  by  them  in 
this  latter  portion  of 
their  career.  Thus,  the 

Only     rational     result     of      The  " original"  canal  leaves  from  the  tip 

OUr      discussion       of     the  of  the   ^,,   the   "duplicate"   from 

higher  up  its  coast. 

canals    is    that   these 

things  are  not  dependent  on  natural  forces  for  their 
action,  but  are  artificial  productions  designed  to  the 
end  they  so  beautifully  serve.  In  the  canals  of  the 
planet  we  are  looking  at  the  work  of  local  intelligence 
now  dominant  on  Mars.  Such  is  what  the  circum- 
stantial evidence  points  to  unmistakably. 

To  detection  of  a  motive  we  now  turn.  And 
here  it  is  our  study  of  planetary  evolution  in  gen- 
eral becomes  of  service.  As  a  planet  ages,  its  sur- 
face water  grows  scarce.  Its  oceans  in  time  dry  up, 
its  rivers  cease  to  flow,  its  lakes  evaporate.  Its  fauna, 
if  it  have  any,  dependent  as  they  are  upon  water  for 
life,  must  more  and  more  be  pushed  to  it  for  that 
prime  necessity  to  existence. 


204      MARS   AS   THE   ABODE   OF   LIFE 

As  the  water  leaves  a  planet,  departing  into  space, 
so  much  of  it  as  does  not  sink  out  of  sight  into  its 
interior  stands  for  a  while  a-tiptoe  in  its  air  before 
taking  final  flight  into  the  sky.  In  the  planet's 
economy  it  has  ceased  to  be  water,  and  become  that 
more  ethereal  thing,  water- vapor.  In  one  way  and 
place  only  does  it  ever  in  any  amount  descend  to 
earth  again  and  take  on  even  transiently  its  liquid 
state.  This  is  in  the  polar  caps.  The  general  mete- 
orologic  circulation  of  the  planet  deposits  it  there 
throughout  the  winter  months.  From  the  cold  of 
the  arctic  latitudes  its  deposition  takes  the  form  of 
snow  or  ice,  and  in  consequence  of  this  solid  state 
is  largely  tethered  to  the  spot  where  it  falls,  remain- 
ing in  situ  until  the  returning  sun  melts  it  in  the 
spring.  This  is  the  state  of  things  on  Mars. 

When  this  unlocking  occurs,  and  while  the  water 
is  in  its  intermediate  liquid  state,  between  not  easily 
transportable  ice  and  ungatherable  vapor,  it  is  in  a 
condition  to  be  moved,  and  may  be  drawn  upon  for 
consumption.  Then,  and  then  only,  is  it  readily 
available  for  use,  and  then,  if  ever,  it  must  be 
tapped. 

Now,  in  the  struggle  for  existence,  water  must  be 
got,  and  in  the  advanced  condition  of  the  planet  this 
is  the  only  place  where  it  is  in  storage  and  whence, 
therefore,  it  may  be  had.  Round  the  semestral  release 


PROOFS   OF   LIFE   ON   MARS          205 

of  this  naturally    garnered    store    everything    in    the 

planet's  organic  economy    must    turn.      There  is  no 

other  source  of  supply.     Its  procuring  depends  upon 

the  intelligence  of  the  organisms  that  stand  in  need 

of   it.       If   these    be    of   a    high 

enough   order  of  mind   to   divert 

it   to   their   ends,  its   using,  from 

a    necessity,   will    become    a    fact. 

Here,  then,  is    a    motive    of  the 

most    compelling    kind    for    the 

tapping  of  the  polar  caps  and  the    DlFFERENG™  °F  ™ 

leading  of  the  water  they  contain    The  Gcalges  is  the  doubie 

over    the  surface   of  the    planet:       Z*J&SXl 

the  primal  motive  of  self-preser-       centre  of  the  disk-    I{ 

will  be  noticed  that  the 


No     incentive     COuld     be  right-hand  line  is  stronger 

than  the  left-hand  one. 

stronger  than  this. 

Our  motive  found  being  of  the  most  drastic  kind, 
it  remains  now  to  examine  whether  it  can  be  put 
into  execution. 

As  a  planet  ages,  any   organisms    upon    it    would  organisms 
share  in  its  development.     They   must   evolve    with  "J^*8^ 
it,  indeed,  or  perish.      At  first  they    change  only  as 
environment  offers   opportunity,  in    a    lowly,  uncon- 
scious way.      But,  as    brain    develops,  they    rise    su- 
perior to  such  occasioning.      Originally  the  organism 
is  the  creature  of  its  surroundings  ;  later  it  learns  to 
make  them  subservient  to    itself.     In    this    way    the 


206      MARS   AS   THE   ABODE   OF   LIFE 

organism  avoids  unfavorableness  in  the  environment, 
or  turns  unpropitious  fortune  to  good  use.  Man 
has  acquired  something  of  the  art  here  on  the  earth, 
and  what  with  clothing  himself  in  the  first  place,  and 
yoking  natural  .forces  in  the  second,  lives  in  comfort 
now  where,  in  a  state  of  nature,  he  would  inconti- 
nently perish. 

Such  adaptation  in  mind,  making  it  superior  to 
adaptation  in  body,  is  bound  to  occur  in  the  organic 
life  on  any  planet,  if  it  is  to  survive  at  all.  For 
conditions  are  in  the  end  sure  to  reach  a  pass  where 
something  more  potent  than  body  is  required  to  cope 
with  them. 
One  species  It  is  possible  to  apply  a  test  to  tell  whether 

supplants  all  ,      , .  _  _  . 

others.  sucn  n^e  existed  or  not.     For  certain  signs  would  be 

forthcoming  were  such  intellect  there.  Increase  of 
intelligence  would  cause  one  species  in  the  end  to 
prevail  over  all  others,  as  it  had  prevailed  over  its 
environment.  What  it  found  inconvenient  or  un- 
necessary to  enslave,  it  would  exterminate,  as  we  have 
obliterated  the  bison  and  domesticated  the  dog.  This 
species  will  thus  become  lord  of  the  planet  and 
spread  completely  over  its  face.  Any  action  it  might 
take  would,  in  consequence,  be  planet-wide  in  its 
showing. 

Now,  such  is  precisely  what  appears  in  the  world- 
spread  system  of  canals.      That  it  joins  the  surface 


PROOFS   OF   LIFE   ON   MARS          207 

from  pole  to  pole  and  girdles  it  at  the  equator  be- 
trays a  single  purpose  there  at  work.  Not  only  does 
one  species  possess  the  planet  but  even  its  subdivi- 
sions must  labor  harmoniously  to  a  common  aim. 
Nations  must  have  sunk  their  local  patriotisms  in  a 
wider  breadth  of  view  and  the  planet  be  a  unit  to  the 
general  good. 

As  the  being  has  conquered  all  others,  so  will  it  at  TO  die  of 
last  be  threatened  itself.  In  the  growing  scarcity  of 
water  will  arise  the  premonitions  of  its  doom.  To 
secure  what  may  yet  be  got  will  thus  become  the 
forefront  of  its  endeavor,  to  which  all  other  questions 
are  secondary.  Thus,  if  these  beings  are  capable  of 
making  their  presence  noticeable  at  all,  their  great 
occupation  should  be  that  of  water-getting,  and 
should  be  the  first,  because  the  most  fundamental, 
trace  of  their  existence  an  outsider  would  be  privi- 
leged to  catch. 

The  last  stage  in  the  expression  of  life  upon  a 
planet's  surface  must  be  that  just  antecedent  to  its 
dying  of  thirst.  Whether  it  came  to  this  pass  by 
simple  exhaustion,  as  is  the  case  with  Mars,  or  by 
rotary  retardation,  as  is  the  case  with  Mercury  and 
Venus,  the  result  would  be  all  one  to  the  planet 
itself.  Failure  of  its  water-supply  would  be  the 
cause.  To  procure  this  indispensable  would  be  its 
last  conscious  effort. 


2o8      MARS   AS   THE   ABODE   OF   LIFE 

End  foreseen.  With  an  intelligent  population  this  inevitable  end 
would  be  long  foreseen.  Before  it  was  upon  the 
denizens  of  the  globe,  preparations  would  have  been 
made  to  meet  it.  And  this  would  be  possible,  for 
the  intelligence  attained  would  be  of  an  order  to  cor- 
respond. A  planet's  water-supply  does  not  depart 
in  a  moment.  Long  previous  to  any  wholesale  im- 
minence of  default,  local  necessity  must  have  begun 
the  reaching  out  to  distant  supply.  Just  as  all  our 
large  cities  to-day  go  far  to  tap  a  stream  or  a  lake, 
so  it  must  have  been  on  Mars.  Probably  the  be- 
ginnings were  small  and  inconspicuous,  as  the  water 
at  first  locally  gave  out.  From  this  it  was  a  step 
to  greater  distances,  until  necessity  lured  them  even  to 
the  pole.  The  very  process,  one  of  addition,  in- 
stead of  one  of  total  synchronous  construction,  seems 
to  show  stereotyped  to  us  in  the  canals.  These  run 
in  their  fashioning  rather  with  partial  than  with  tele- 
ologic  intent,  giving  as  much  concern  to  halfway 
points  as  to  the  goal  itself,  although  in  their  action 
now  they  are  totally  involved.  The  thing  was  not 
done  in  a  day,  and  by  that  very  fact  stamps  the 
more  conclusively  its  artificial  origin. 

The  ability  of  beings  there  to  construct  such 
arteries  of  sustenance,  two  considerations  will  help 
to  make  comprehensible :  one  of  these  minifies  the 
work,  the  other  magnifies  the  workers.  In  the  first 


PROOFS   OF   LIFE   ON   MARS          209 

place,  it  is  not  what  we  see  that  would  have  to  be 
constructed.  The  object  of  endeavor  is  not  only  the 
water  itself,  but  the  products  that  water  makes  pos- 
sible. It  is  vegetation  which  is  matter  of  imme- 
diate concern,  water  being  of  mediate  employment. 
This,  then,  is  what  would  probably  show.  Just  as 


NORTHEAST  CORNER  OF  AERIA,  JULY  2-5,  1907 

on  the  earth  it  is  the  irrigated  strip  of  reclaimed 
desert,  and  not  the  Nile  itself,  which  would  make 
its  presence  evident  across  interplanetary  space.  If 
these  lines  are  irrigated  bands  of  planting,  the  ver- 
tebral canal  would  be  a  mere  invisible  thread  in  the 
midst  of  that  to  which  it  gave  growth.  This  alone 
would  have  to  be  made,  and  indeed  it  would  prob- 
ably be  covered  to  prevent  evaporation. 


210      MARS   AS   THE   ABODE   OF   LIFE 

Now,  we  have  evidence  that  the  canals  are  thus 
composed  of  nerve  and  body.  When  they  lie  down, 
they  do  not  entirely  vanish.  Under  the  visual  con- 
ditions of  Flagstaff  they  may  still  be  made  out  in 
their  dead  season,  the  mere  skeletons  of  themselves 
as  they  later  fill  out.  And  even  so  we  do  not  ac- 
tually see  the  nerve  itself. 

For  the  construction  of  these  residuary  filaments 
we  have  a  plethora  of  capabilities  to  draw  upon  :  in 
the  first  place,  beings  on  a  small  planet  could  be 
both  bigger  and  more  effective  than  on  a  larger  one, 
because  of  the  lesser  gravity  on  the  smaller  body. 
An  elephant  on  Mars  could  jump  like  a  gazelle. 
In  the  second  place,  age  means  intelligence,  enabling 
them  to  yoke  nature  to  their  task,  as  we  are  yoking 
electricity.  Finally,  the  task  itself  would  be  seven 
times  as  light.  For  gravity  on  the  surface  of 
Mars  is  only  about  38  per  cent  of  what  it  is  on 
the  surface  of  the  earth;  and  the  work  which  can 
be  done  against  a  force  like  gravity  with  the  same 
expenditure  of  energy  is  inversely  as  the  square  of 
that  force.  A  ditch,  then,  seven  times  the  length 
of  one  on  earth  could  be  dug  as  easily  on  Mars. 

With  this  motive  of  self-preservation  for  clew,  and 
with  a  race  equal  to  the  emergency,  we  should  ex- 
pect to  note  certain  general  phenomena.  Both  polar 
caps  would  be  pressed  into  service  in  order  to  utilize 


PROOFS   OF   LIFE   ON   MARS          211 

the  whole  available  supply  and  also  to  accommodate 
most  easily  the  inhabitants  of  each  hemisphere.  We 
should  thus  expect  to  find  a  system  of  conduits  of 
some  sort  world-wide  in  its  distribution  and  running 
at  its  northern  and  southern  ends  to  termini  in  the 
caps.  This  is  precisely  what  the  telescope  reveals. 
These  means  of  communication  should  be,  if  possible, 
straight,  both  for  economy  of  space  and  of  time,  it 
being  especially  necessary  to  avoid  any  wasteful 
evaporation  on  the  road.  Construction  of  such  would 
needs  be  very  difficult,  if  not  impracticable,  on  earth, 
owing  to  the  often  mountainous  character  of  its  sur- 
face. But  on  Mars  this  is  not  the  case.  As  we  have 
seen,  there  are  fortunately  no  mountains  on  Mars. 
Thus  the  great  obstacle  to  canals,  and,  in  conse- 
quence, the  great  obstacle  to  their  acceptance,  is 
providentially  removed.  Terrain  offers  the  least  of 
objections,  terror  the  greatest  of  spurs,  to  their  con- 
struction. 

Thus  we  see  that  not  only  should  the  execution 
be  possible,  but  that  it  should  exhibit  precisely  the 
phenomena  we  see. 

It  would    be    interesting,  doubtless,  to    learn    how  Further 
are  bodied  these  inhabitants  that  analysis  reaches  out  pher 
to  touch.      But  body  is  the  last  thing  we  are  likely 
to  know  of  them.     Of  their  mind    as    embodied  in 
their  works,  we  may  learn  much  more ;  and,  after  all, 


212      MARS   AS   THE   ABODE   OF   LIFE 

is  not  that  the  more  pregnant  knowledge  of  the  two  ? 
Something  of  this  we  have  surveyed  together.  But 
beyond  the  lime-light  of  assured  deduction  stand 
many  facts  awaiting  their  turn  to  synthetic  coordina- 
tion which  we  have  not  touched  upon.  It  is  proper 
to  mention  some  of  them  under  due  reserve,  for 
they  constitute  the  bricks  which,  with  others  yet  to 


THE  CARETS  OF  MARS 

Carets  at  the  borders  of  the  "  seas  ";  showing  those  of  Icarii  Luci  and  their  resem- 
blance, in  miniature,  to  the  two  forks  of  the  Sabaeus  Sinus.  These  carets  are 
distinctive  phenomena,  marking  the  entrance  of  the  canals  from  the  dark 
regions  into  the  light.  They  are  found  at  such  points,  and  at  such  points  only. 

come,  will   some   day    be    built    up    into   a    housing 
whole. 

Not  least  of  these  are  those  strange  caret-shaped 
dark  spots  at  the  points  where  the  canals  leave  the 
dark  regions  to  adventure  themselves  into  the  light. 
No  canal  thus  circumstanced  in  position  is  apparently 
without  them,  and,  unlike  the  oases,  they  do  not 
show  round.  On  the  theory  of  canalization  they  are 


PROOFS   OF   LIFE   ON   MARS          213 

certainly  well  placed.  We  have  seen  that  the  blue- 
green  regions  and  the  ochre  ones  lie  undoubtedly 
at  different  levels,  the  former  standing  much  lower 
than  the  latter. 

Here,  then,  should  occur  difficulties  in  canalization 
which  would  have  to  be  overcome.  Are  these,  then, 

the  evidence  of  their 

surmounting  ?     They 

certainly  suggest  the  -^L^  '* 

fact.  *"»T*"I"*% 

Then    the    oases 
themselves    lure    our     L 

thoughts  afield.      Im-          MouTHS  OF  EUPHRATES  AND  PHISON 

The  drawing  shows  the  way  in  which  each 
portant  Centres  tO  the  branch  of  the  two  double  canals  enters  the 

canal  system  they  are  desert  from  a  common  point  of  departure* 

on  their  face.  But,  if  centres  to  that,  they  should 
bear  a  like  relation  to  what  fashioned  the  canals. 
That  they  dilate  and  dwindle  seasonally  points  to 
vegetation  as  their  chief  constituent,  whence  their 
name.  But  behind,  and  informing  this,  must  be  the 
bodied  spirit  of  the  whole.  We  are  certainly  justi- 
fied in  regarding  them  as  the  apple  of  the  eye  of 
Martian  life  —  what  corresponds  with  us  to  centres 
of  population. 

An  interesting  phenomenon  about  the  oases  makes 
this  the  more  probable.  Observation  discloses  that 
the  oases  are  given  to  change  both  of  size  and  tone. 


2i4      MARS   AS   THE   ABODE   OF   LIFE 

They  fade  at  certain  seasons,  retaining  only  a  rela- 
tively diminutive  dark  kernel.  They  are  thus  formed 
of  two  parts,  pulp  and  core.  The  pulp  itself  indi- 
cates vegetation,  since  it  follows  the  same  laws  as  the 
canals ;  the  core  may  well  be  the  evidence  of  the 
permanent  population.  That  the  largest  are  some 
75  miles  across,  seems  to  give  sufficient  space 
for  living  and  the  means  to  live.  If  our  cities 
had  to  be  their  own  sources  of  supply,  they  might 
well  be  of  this  size.  As  it  is,  Tokio  is  ten  miles  by 
ten,  and  London  yet  larger.  But  we  must  in  this 
be  careful  to  part  surmise  from  deduction. 

In  our  exposition  of  what  we  have  gleaned  about 
Mars,  we  have  been  careful  to  indulge  in  no  specula- 
tion. The  laws  of  physics  and  the  present  knowl- 
edge of  geology  and  biology,  affected  by  what 
astronomy  has  to  say  of  the  former  subject,  have 
conducted  us,  starting  from  the  observations,  to  the 
recognition  of  other  intelligent  life.  We  have  care- 
fully considered  the  circumstantial  evidence  in  the 
case,  and  we  have  found  that  it  points  to  intelli- 
gence acting  on  that  other  globe,  and  is  incompatible 
with  anything  else.  We  have,  then,  searched  for 
motive  and  have  lighted  on  one  which  thoroughly 
explains  the  evidence  that  observation  offers.  We 
are  justified,  therefore,  in  believing  that  we  have  un- 
earthed the  cause  and  our  conclusion  is  this :  that  we 


PROOFS   OF   LIFE   ON   MARS       •  215 

have  in  these  strange  features,  which  the  telescope 
reveals  to  us,  witness  that  life,  and  life  of  no  mean 
order,  at  present  inhabits  the  planet. 

Part  and  parcel  of  this  information  is  the  order  of 
intelligence  involved  in  the  beings  thus  disclosed. 
Peculiarly  impressive  is  the  thought  that  life  on  an- 
other world  should  thus  have  made  its  presence 
known  by  its  exercise  of  mind.  That  intelligence 
should  thus  mutely  communicate  its  existence  to  us 
across  the  far  stretches  of  space,  itself  remaining  hid, 
appeals  to  all  that  is  highest  and  most  far-reaching 
in  man  himself.  More  satisfactory  than  strange  this; 
for  in  no  other  way  could  the  habitation  of  the 
planet  have  been  revealed.  It  simply  shows  again 
the  supremacy  of  mind.  Men  live  after  they  are 
dead  by  what  they  have  written  while  they  were  alive, 
and  the  inhabitants  of  a  planet  tell  of  themselves 
across  space  as  do  individuals  athwart  time,  by  the 
same  imprinting  of  their  mind. 

Thus,  not  only  do  the  observations  we  have  Our  life  not 
scanned  lead  us  to  the  conclusion  that  Mars  at  this 
moment  is  inhabited,  but  they  land  us  at  the  further 
one  that  these  denizens  are  of  an  order  whose  ac- 
quaintance was  worth  the  making.  Whether  we 
ever  shall  come  to  converse  with  them  in  any  more 
instant  way  is  a  question  upon  which  science  at 
present  has  no  data  to  decide.  More  important  to 


216      MARS   AS   THE   ABODE   OF   LIFE 

us  is  the  fact  that  they  exist,  made  all  the  more 
interesting  by  their  precedence  of  us  in  the  path  of 
evolution.  Their  presence  certainly  ousts  us  from 
any  unique  or  self-centred  position  in  the  solar  sys- 
tem, but  so  with  the  world  did  the  Copernican 
system  the  Ptolemaic,  and  the  world  survived  this 
deposing  change.  So  may  man.  To  all  who  have 
a  cosmoplanetary  breadth  of  view  it  cannot  but  be 
pregnant  to  contemplate  extra-mundane  life  and  to 
realize  that  we  have  warrant  for  believing  that  such 
life  now  inhabits  the  planet  Mars. 

A  sadder  interest  attaches  to  such  existence  :  that 
it  is,  cosmically  speaking,  soon  to  pass  away.  To 
our  eventual  descendants  life  on  Mars  will  no  longer 
be  something  to  scan  and  interpret.  It  will  have 
lapsed  beyond  the  hope  of  study  or  recall.  Thus  to 
us  it  takes  on  an  added  glamour  from  the  fact  that 
it  has  not  long  to  last.  For  the  process  that 
brought  it  to  its  present  pass  must  go  on  to  the 
bitter  end,  until  the  last  spark  of  Martian  life  goes 
out.  The  drying  up  of  the  planet  is  certain  to 
proceed  until  its  surface  can  support  no  life  at  all. 
Slowly  but  surely  time  will  snuff  it  out.  When  the 
last  ember  is  thus  extinguished,  the  planet  will  roll 
a  dead  world  through  space,  its  evolutionary  career 
forever  ended. 


APPEARANCE  OF  MARS  IN  1905 


PART    II 
NOTES 


PART  II.     NOTES 


ON  MOMENT  OF  MOMENTUM 

The  momentum  of  a  body  is  the  quantity  of  motion  it 
contains,  which  is  its  mass  multiplied  by  its  velocity,  i.e. 
the  sum  of  the  motions  of  all  the  particles  composing  it. 
Its  moment  of  momentum  about  any  point  is  this  quantity 
into  the  perpendicular  from  the  point  upon  its  instanta- 
neous course.  It  is  thus 

m  -  v  •  r, 
where  m  is  its  mass  ; 

v  its  velocity  at  right  angles  to  the  shortest  distance 

to  the  point  ; 

r  its  perpendicular  distance  from  the  point. 
Suppose,  now,  two  bodies,  one  x  times  the  mass  of  the 
other,  to  be  revolving  round  each  other  in  circles  and,  for 
simplification,  that  both  are  homogeneous  and  non-rotating. 
If  m  be  their  united  mass,  the  relative  velocity  of  one 
about  the  other  is 


for  a  circular  orbit,  £2  being  the  unit  force  at  unit  distance. 
Then  the  moment  of  momentum  of  the  system  round  its 
centre  of  gravity  is 


since  the  velocities  of  the  bodies  about  their  centre  of 
gravity  and  their  distances  from  it  are  inversely  as  their 
masses. 

219 


220      MARS   AS   THE   ABODE   OF   LIFE 

To  find  what  partition  renders  this  quantity  a  maximum, 
we  must  differentiate  it  with  regard  to  x  and  put  the  deriv- 
ative equal  to  zero.  Thus 


dx  dx 

whence  x  =  ^  ,  or  the  masses  must  be  equal.     That  this 
gives  a  maximum  is  shown  by  the  second  derivative, 

d(  i  —  2  x}  _ 
dx 

Applying  this  to  Jupiter  and  the  Sun,  we  see  that  the 
moment  of  momentum  of  the  two  is  only  ^|^  of  what  it 
might  be  were  the  mass  otherwise  distributed  to  get  the 
greatest  effect.  In  other  words,  the  quantity  of  motion  in 
the  solar  system  is  almost  the  least  possible  ;  and  from  the 
principle  of  the  conservation  of  the  moment  of  momentum 
of  a  system  of  bodies  by  their  mutual  action,  this  has 
always  been  so. 

For  the  system  «  Centauri,  though  the  mass  of  its  two 
suns  is  only  2.14  that  of  the  Sun's,  the  moment  of  momen- 
tum is  about  2000  times  as  great. 


THE  CONNECTION  OF  METEORITES  WITH  THE  SOLAR 
SYSTEM 

The  speed  with  which  meteorites  are  observed  to  enter 
the  Earth's  atmosphere  is  telltale  of  their  relationship  to 
the  solar  system.  For  the  velocity  of  a  body  moving  on  a 
parabolic  orbit  with  regard  to  the  Sun,  the  greatest  he  can 
control,  may  be  calculated,  and  this  velocity  compared  with 
the  observed  ones.  A  solution  of  it  by  the  writer  by  a 
method  of  interest  in  itself,  that  of  a  rotating  field  of  force, 


NOTES  221 

has  been  published  in  the  Astronomical  Journal  for  April 
17,  1908,  and  is  here  reproduced. 

Consider  a  system  of  axes  £,  77,  £,  of  which  £  and  77  rotate 
about  £  with  a  uniform  angular  spin  n.  Take  the  origin 
at  the  Sun,  and  let  the  £  axis  continually  pass  through  the 
Earth  supposed  to  travel  in  a  circle.  Then  the  space 
velocities  u,  v,  and  w  expressed  in  the  moving  axes  £,  77, 
and  £  respectively,  or  the  space  rates  of  change  of  f,  77,  £, 
are 

u  =      —  n-, 


where  the  accents  denote  the  derivatives  with  respect  to 
the  time.  Similarly  the  accelerations  or  the  forces  which 
they  measure,  X,  Y,  and  Z  expressed  in  the  same  axes,  are 

X=u'  -nv, 
Y=v'-nu, 
Z  =  wf. 

Substituting  for  u,  v,  and  n  in  the  last  equations  their 
values  from  the  first,  we  have 


Let  U  be  the  potential  of  the  forces, 

dU      Y    dU      v       ,  dU 
—  •  =  ^,  —  =  F,  and  —  = 


222      MARS   AS   THE   ABODE   OF   LIFE 

In  the  rotating  field  of  force  [7  is  a  function  of  f,  77,  and 
£  only,  since  the  time  has  been  eliminated  by  the  rotation, 
Therefore 

dU=dU    d%      dJJ    dn.dU    tf 

dt       d%  '  dt      dt]  '  dt       d£  '  di 

If  the  equations  of  motion  be  multiplied  by 


, 

dt       dt  dt 

respectively,  and  added,  they  admit  of  an  integral  first 
found  by  Jacobi, 

^2_w2r2=2  [/+C, 

in  which  vl  =  velocity  of  the  particle  relatively  to  the  mov- 

ing axes,  its  relative  not  its  space  rate, 
and  r=  its  distance  from  the  origin  reckoned  by  the 

same. 

We  shall  suppose  the  particle  to  be  moving  in  the  plane 
of  the  planet's  motion,  that  of  f,  77.  The  velocity  of  en- 
counter with  the  planet  is  thus  made  the  greatest  or  the 
least  possible,  according  as  the  particle  overtakes  the 
planet  or  meets  it  head  on. 

Calling  V  the  space  velocity  of  the  particle,  that  is  the 
velocity  with  regard  to  fixed  axes,  and  A  the  moment  of 
momentum  with  regard  to  the  same  at  the  moment,  we 
have 

F2  =  v?  +  2  nr  cos  av1  +  nzr*, 

in  which  a  is  the  angle  between  vl  and  nr—  hence 
r  cos  a  =pi,  the  perpendicular  from  the  origin  upon  the 
particle's  line  of  motion  in  space,  but  A  =  v^p  +  nr*  by 
taking  moments  about  the  origin,  of  the  particle's  motion 
in  the  rotating  plane  plus  that  of  the  plane  itself, 


whence  Vz  —  2  nA  =  2  U+  C. 


NOTES  223 

We  determine  C  by  the  consideration  that  for  a  parabola 
at  infinity, 

F=  0  and  U=  0, 


whence  —  since 


where  /  is  the  parameter  of  the  parabola  and  c  the  radius 
of  the  planet's  orbit. 

Suppose   now   the   particle  to   be  just  overtaking  the 
planet  from  behind,  /  will  very  approximately  be  2  r,  while 

A  =  v^p  +  nr* 

will  =  V-  v^  -p  +  nr\ 

in  which  z>0  is  the  velocity  of  the  planet  in  its  orbit, 
then  vQp  =  nrz 

and  A  =  r  •  V. 

2nA=2nr-  V. 
Let  M=  mass  of  the  Sun, 
m  =  mass  of  the  planet, 
r=  c=  radius  of  the  planet's  orbit, 
p  =  distance  from  the  Earth's  centre  to  where  the 

meteor  enters  the  atmosphere,  which  for  round  numbers 
we  may  take  at  3958.8  +41  miles,  or  4000  miles. 
Then  the  attraction  of  the  Sun  on  the  particle  is 

—  —  very  approximately, 
that  of  the  planet  on  the  particle 


224      MARS   AS   THE    ABODE   OF   LIFE 

and  that  of  the  planet  on  the  Sun  which  is  to  be  applied 
reversed  to  bring  the  Sun  to  rest, 


This  latter  force  acts  only  in  the  line  f. 
Consequently,  since  X  and   Y  are  functions  of  f  and 
only,  not  involving  t, 


r       p       r2 
our  equation  becomes 


Completing  the  square  on  the  left-hand  side  and  extract- 
ing the  square  root,  we  have 


p 

Letting  M=  I  and  r=  i  and  determining  k,  the  coef- 

ficient of  proportionality,  so  that  V  comes  out  in  miles  per 

second,  —  for  k  enters  with  the  masses  as  kzM  unless  the 

unit  of  time  be  canonically  chosen,  we  find,  since  z/0  =  nr, 

V—  VQ  =  the  velocity  relative  to  the  Earth 

=  10.321  miles  a  second  when  the  particle 
overtakes  the  Earth. 

The  Earth's  effect  in  increasing  the  velocity  which  rin 
this  case  is  the  greatest  possible  is 

28.822  —  26.163  —  2.659  miles  a  second. 

In  the  other  case,  when  the  Earth  encounters  the  particle 
head  on,  vl  becomes  negative  and  C  negative. 


—  2nA  =  + 


NOTES  225 

and 


r       p 
and 


r       p 

whence   V+  2/0  =  45.197  miles  a  second,  and  the  effect  of 
the  Earth  in  increasing  the  meteor's  velocity 

=  26.696  -  26.163  =  0.533  mile  a  second. 

The  geometric  explanation  why  the  velocities  cannot  be 
directly  added  is  that  when  each  body  is  supposed  to  act 
alone  the  times  involved  in  their  actions  are  different, 
while  when  they  act  together  these  are  naturally  the  same. 
In  the  latter  case  the  velocity  due  the  Sun  hurries  the 
particle  through  the  space  faster  than  the  Earth's  pull 
alone  could,  and  so  gives  the  Earth  less  time  to  act. 

Now  if,  instead  of  moving  in  a  parabolic  or  controlled 
orbit,  the  meteor  were  travelling  in  a  hyperbolic  or  uncon- 
trolled one,  its  speed  of  encountering  the  earth  would  be 
greatly  increased. 

But  there  are  no  instances  of  meteors  meeting  the  Earth 
at  speeds  exceeding  or  even  equalling  45.1  miles  a  second. 
From  this  we  perceive  that  they  are  not  visitants  from 
outer  space,  travellers  from  other  suns,  but  are  all  part 
and  parcel  of  the  Sun's  retinue,  kin  to  Jupiter  and  the 
Earth,  the  remains,  indeed,  of  those  from  which  the 
planets  were  built  up. 

3 

THE  HEAT  DEVELOPED  BY  PLANETARY  CONTRACTION 

To  find  the  heat  evolved  by  the  aggregation  of  particles 
into  a  planetary  mass  and  the  subsequent  shrinking  of 
that  mass  upon  itself,  we  first  find  the  work  done  by  the 
contraction  and  then  evaluate  it  in  terms  of  heat. 


226      MARS   AS   THE   ABODE   OF   LIFE 

Let  M'  =  mass  within  a  radius  r ; 

then  the  work  done  by  a  shell  dM'  contracting  under  the 
pull  of  M',  the  mass  inside  it,  from  infinity  to  the  radius 
ris 

CT  t?M'dM'  _  JPM'dM' 
i  _        _  , 

«/oo  y*  y 

where  kz  is  the  force  between  unit  masses  at  unit  distance. 
If  the  sphere  be  supposed  homogeneous  and  M  be  the 
mass  of  the  nebula  of  radius  a  at  any  time, 

M'  =  M-^.  dM'  =  3  Mr-dr. 


CaPM'dM'       ra$&Mz  4  ,       3  ,0^/2 

=  I    2 — - — r*dr=±kz ,  (i) 

Jo  r  Jo       06  $      a 

the  work  done. 

But  the  sphere  is  really  heterogeneous,  and  to  determine 
the  function  of  the  density  we  proceed  as  follows  : 

The  attraction,  A,  of  the  mass  M'  upon  the  shell  dM'  is: 


where  p  =  the  density.     Let  /  =  the  pressure  at  the  point. 
Then  dp  =  -pAdr, 


whence  dp  = 

Now,  as  Laplace  says,  both  solids  and  liquids  resist  com- 
pression more  the  more  they  are  compressed.  The  most 
simple  expression  of  this  fact  is  : 

dp  =  hpdp, 

which  is  Laplace's  formula. 

The  Roche  formula  hardly  gains  in  exactness  enough  to 
offset  its  greater  complexity,  as  Tisserand  has  shown. 


NOTES  227 

Whence,  substituting  Laplace's  value  for  dp  above, 


h 
Differentiating  this,  we  have 


h 
The  solution  of  this  equation  is,  calling  —  —  =m, 

pr=c  sin  mr  +  cl  cos  mr\ 

but  since  the  density  p  must  remain  finite  at  the  centre 

,  i  c  sin  mr  ,  >. 

where  r  =  o,  c^  =  o\  and     p  —  --  (2) 

To  find  the  two  unknown  parameters  c  and  m,  and  thus 
//,  we  have  for  the  Earth,  if  pl  denote  the  density  at  the  sur- 
face where  r  =  I, 

ft  =  c  sin  m  =  2.74,  supposed  all  rock,  (3) 

or  2.5,  allowing  for  the  ocean; 
and  also  since  the  mean  density  =  5.53, 

*!!.*.  (4) 

3         •'o 

In  the  determination  of  the  work  done,  we  must  write 

c  sin  m  - 
a 


Then  dM'  =  4  irr*dr  .  —  smm  -• 

r  a 

M1  =  4  TTCIC  \     r  sin  m  -•  dr 
JQ  a 

a8c  f  •         r          r  r~\ 

=  4  TT  —  -  sm  m  —  m  -  cos  m  - 
nr  [_  a          a  aj 


228      MARS   AS   THE   ABODE   OF   LIFE 


sin  m  --  m  -  cos  m  - 


i  Ti/rl  n/r 

whence  M'  =  M 


sin  m  —  m  cos  m 


. 

sin  m  —  m  cos  m 


(sin  m  —  m  cos 


sin        cos 
#          «  J 


x   . 
2  (sin  m  —  m  cos  w)2  « 

Since  the  work  done  by  a  mass  Jf  in  cooling  /  degrees  is 
Majt,  where  a-  is  the  specific  heat  of  the  body, 

and  J  the  mechanical  equivalent  of  heat, 
in  the  case  of  a  homogeneous  body 

t  —  —  •  -  for  contraction  from    oo  to   the 

5     oja 
radius  a, 


and  therefore  t  =  ±-?^-(i  --.)  for  contraction  from  the 
5    <rja  a 

radius  a'  to  a.  In  the  case  of  heterogeneity,  the  right- 
hand  members  of  the  equations  should  be  multiplied  by 
the  ratio  of  (5)  to  (i). 

During  the  evolution  of  the  heat,  radiation  was  steadily 
draining  it  away,  according  to  the  fourth  power  of  the  sur- 
face temperature  (Stefan's  law).  Convection  meanwhile 
was  going  on  from  the  inside  out,  the  quantity  delivered 
from  one  layer  to  the  next  being  proportionate  to  their 
differences  of  temperature  dT,  while  this  difference  was 
itself  dependent  on  the  areas  involved,  which  were  as 

^5 ,  and  therefore  their  increase  in  the  ratio  '-LL.  If  we 
r?  r, 


NOTES 


229 


assume  in  consequence  that  the  surface  was  never  hotter 
than  10,000°  F.  or  5556°  C.,  we  shall  have  a  heat  sufficient 
to  explain  all  the  metamorphic  and  volcanic  phenomena 
exhibited  by  geology. 

ENERGY  LET  LOOSE  DURING  CONTRACTION.      EVALUATED  IN  HEAT 


CONTRACTION  FROM  INFINITY 
TO  PRESENT  STATE 

BODY    SUPPOSED    HOMOGE- 
NEOUS. 
DEGREES  FAHRENHEIT 

BODY  SUPPOSED  HETERO- 
GENEOUS   ACCORDING  TO 

LAPLACE'S  ASSUMPTION. 
DEGREES  FAHRENHEIT 

Stone 

Iron 

Stone 

Iron 

Earth  
Mars 

80,520 
16,303 
3,665 

11,262 
584 

44 

146,400 
29,642 
6,664 

20,476 
1,062 
80 

89,377 
17,118 

3,812 

12,501 
613 
46 

162,504 
31,124 
6,931 

22,728 
I,II5 
83 

CONTRACTION  FROM  METEORIC 
DENSITY  TO  PRESENT  STATE 

Earth  3.5  to  5.5 
Mars    3.5  to  0.71  x  5.5 
Moon  3.5  to  0.66  x  5.5 

THE  HEIGHTS  OF  MOUNTAINS  ON  THE  MOON 

For  simplification  consider  a  mountain  on  the  apparent 
lunar  equator  near  the  sunrise  or  sunset  edge  of  the  disk 
when  the  Moon  shows  half-full.  Then,  if  /  =  the  apparent 
distance  its  star-like  summit  seems  off  the  terminator,  — 
the  general  dividing  line  between  sunlight  and  shade : 

r  =  the  radius  of  the  Moon ; 


we  have 


//  =  the  height  of  the  peak ; 
/2  +  rz  =  (r  +  lif. 


230      MARS    AS   THE   ABODE   OF   LIFE 

The  lunar  diameter  being  2160  miles,  this  gives  for  a 
mountain  four  miles  high  an  apparent  isolation  from  the 
terminator  of  93  miles,  or  23  times  its  height.  For  one  a 
mile  high,  the  distance  is  46  miles  or  46  times  its  height. 
Thus  the  principle  affords  an  indirect  kind  of  magnifica- 
tion, relatively  greater  and  greater  inversely  as  the  square 
root  of  the  height. 

5 
HEAT  ACQUIRED  BY  THE  MOON 

In  the  expression  (5)  for  the  work  done  by  contraction 
in  the  case  of  heterogeneity,  m  will  vary  with  each  planet, 
since  its  determination  depends  upon  both  the  surface  and 
the  mean  density  of  the  contracting  body.  For  the  surface 
density  of  the  Moon  we  have  a  ground  surface  entirely ; 
that  is,  one  of  rock.  In  consequence,  we  may  perhaps 
estimate  it  as  being  that  of  the  rocky  exterior  of  the  Earth, 
or  2.7,  water  being  unity.  The  mean  lunar  density  is  3.65. 
Putting  these  values  in  place  of  those  of  the  Earth  in  (3) 
and  (4),  we  get  from  the  new  (5)  with  the  new  m'  the  value 
for  the  Moon's  contracted  heat  given  in  the  table. 

Since  the  rate  of  changes  of  the  concentric  shells  is  as 

!L, while  dr  is  taken  constant,  the  gradient  of  temperature 
fi 

from  the  inside  out  will  be  greater,  the  smaller  the  body, 
and  convection  in  it  be  more  rapid.  Also  its  surface  being 
larger  relatively  to  its  volume,  it  would  on  that  account 
radiate  more.  That  surface,  therefore,  could  never  attain 
the  degree  of  warmth  of  the  other's  in  spite  of  the  greater 
radiation  at  higher  temperatures.  We  shall  probably  be 
within  the  mark  if  we  take  the  surface  temperature  at  its 
maximum  as  proportionate  to  the  total  heat  evolved.  This 
would  give  on  the  supposition  of  10,000°  F.  for  the  Earth, 


NOTES  231 

400°  F.  Abs.  for  the  Moon,  01—59°  below  the  freezing-point,  a 
temperature  quite  incompatible  with  volcanic  phenomena. 


SURFACE  HEAT  OF  MARS 

For  Mars,  where  again  the  surface  is  wholly  ground, 
we  have  p,=  2.7,  while  the  mean  density  of  the  planet  is 
3.93.  With  these  data  we  obtain  a  new  m"  and  the 
value  for  the  heat  evolved  given  in  the  table  under 
heterogeneity. 

Following  the  same  course  as  with  the  Moon,  we  get  a 
surface  temperature  for  Mars  at  its  maximum  of  2000°  F. 
This  is  just  below  the  melting-point  of  (cast)  iron,  which 
is  2160°  F.  Such  a  temperature  is  insufficient  for  the  dis- 
play of  metamorphic  or  of  volcanic  action  such  as  oc- 
curred on  Earth.  For  the  like  reason  the  crumpling  of 
the  crust  in  consequence  of  the  planet's  parting  with  its 
internal  heat  must  have  been  much  less  pronounced. 


7 

THE  BOILING-POINT  OF  WATER  ON  MARS 

The  boiling-points  of  liquids  are  functions  both  of  the 
temperature  and  the  pressure ;  a  lower  temperature  being 
sufficient  to  cause  ebullition  if  the  pressure  be  less.  On 
the  kinetic  theory  of  gases  the  cause  of  this  is  at  once 
comprehensible.  Boiling  means  that  the  particles  of  the 
liquid  generally  have  attained  speed  enough  to  throw  off 
the  restraint  of  their  neighbors  and  leave  the  surface. 
Release  may  come  about  through  increase  of  velocity,  or, 
in  other  words,  increase  of  temperature,  since  temperature 
is  only  another  expression  for  the  mean  velocity-square 


232      MARS   AS   THE   ABODE   OF   LIFE 

of  the  particles ;  or  by  decrease  of  restraint,  which  means 
decrease  of  the  pressure  upon  them. 

Gravity  on  the  surface  of  Mars  is  only  38  per  cent  of 
that  at  the  surface  of  the  Earth,  and  if  the  amount  of 
Martian  air  per  unit  of  surface  be  f  that  of  the  Earth,  as 
later  we  shall  see  to  be  probable,  the  pressure  there 
would  be 

/  =  M,g,  =  0.09  Mg, 

where  the  unaccented  letters  refer  to  the  Earth,  the  ac- 
cented to  Mars.     Whence  the  boiling-point  would  be 

44°  C.  or  m°F. 


THE  PALEOZOIC  SUN 

M.  Blondet's  explanation  of  the  greater  warmth  of 
paleozoic  times  was  that  the  Sun  then  occupied  a  space 
large  enough  to  be  able  to  shine  on  the  pole  even  in  mid- 
winter. To  do  this,  the  semidiameter  of  the  Sun  must 
have  subtended  at  the  centre  of  the  Earth  an  angle  equal 
to  the  tilt  of  the  pole  away  from  the  Sun,  or  an  angle  of 
23°  27'.  This  would  give  it  a  semidiameter  of  37,000,000 
miles,  or  a  million  miles  larger  than  the  mean  distance  of 
Mercury. 

Its  present  mean  density  is  1.39  times  that  of  water. 
The  density  of  hydrogen,  the  lightest  known  gas,  is 
0.0000895  that  of  water  at  o°  C.  and  under  a  pressure  of 
760  mm.  at  Lat.  45°.  The  present  diameter  of  the  Sun 
is  866,000  miles.  Its  density  then  must  therefore  have 
been 


.39.  _  0.0000,78, 

37oooooo3 


or  \  that  of  hydrogen. 


NOTES  233 

Such  tenuous  matter  could  hardly  have  given  out  any 
heat  at  all.  This  is  one  insuperable  objection.  A  second 
is  that  to  suppose  that  the  Earth  can  have  condensed  to 
a  solid  state  while  the  Sun  still  remained  of  such  gaseous 
tenuity,  its  material  more  sparse  than  that  of  any  known 
gas,  is  to  violate  every  conception  of  evolution.  The 
thing  is  mechanically  impossible. 

When  we  reflect  that  so  eminent  a  geologist  as  M.  de 
Lapparent*  espoused  M.  Blondet's  hypothesis,  we  see  how 
necessary  to  geologic  conceptions  is  a  foundation  for 
them  in  astronomy. 

9 

EFFECT  ON  THE  EARTH  OF  THE  SUPPOSED  PALEOZOIC  SUN 

As  impossible  the  supposed  paleozoic  Sun  proves  from 
the  point  of  view  of  the  Earth.  For  on  critical  examination 
it  turns  out  quite  incapable  of  the  climatic  effect  attributed 
to  it,  even  supposing  it  emitted  heat  enough  to  have  any 
effect  at  all. 

To  calculate  its  zonal  influence  we  proceed  as  follows  : 
If  a  =  coaltitude  of  the  Sun,  its  insolation  at  the  moment 
at  the  confines  of  the  atmosphere  is  as  cos  a.  The  relative 
amount  of  the  total  insolation  at  a  given  latitude  and  for  a 
given  declination  during  twenty-four  hours,  supposing  the 
Sun  a  point,  and  calling  the  insolation  at  the  equator  at  the 
equinox  unity,  is  expressible  by  spherical  triangles  as : 

/•  cos"1  ( -  cot  b  •  cot  c)  /•cos"1  (-  cot  6  •  cot  c) 

I  =  2  I  cosa  -dA  =  2  I  cosbcosc-dA  +  sin  ItsinccosA  •  dA 

«/0  »/0 

,  ,  ,     .  .^    cos-1  (-cot  b  -cote) 

=  2(cos  b  cos  c  •  A  +  sin  b  sin  c  •  sm  A)  , 

where  b  =  the  colatitude  of  the  place, 

c  =  the  codeclination  of  the  sun, 
A  =  the  hour  angle  from  noon ; 

*  "  Traite  Elementaire  de  Geologic,"  par  De  Lapparent. 


234     MARS   AS   THE   ABODE   OF   LIFE 

the  limits  of  the  integration  being  the  meridian,  where  A  =  o 
and  the  horizon  where  a  =  90°  and  its  cosine  o,  whence 

o  =  cos  b  cos  c  +  sin  b  sin  c  cos  A, 
or  A  =  cos"^—  cot  b  cot  c\ 

But  the  area  of  the  supposed  paleozoic  Sun  cannot  be 
considered  a  point  because  of  its  size.  To  deduce  its  effect 
each  bit  of  it  which  rises  above  the  horizon  of  the  place 
must  be  taken  into  account  and  given  weight  inversely  as 
the  square  of  its  distance  off. 

For  our  purpose,  however,  a  sufficiently  accurate  ap- 
proximation may  be  got  by  taking  in  each  determination 
what  would  be  the  centre  of  mass  of  the  solar  zone  above 
the  latitude  of  the  lowest  central  point  visible  supposing 
the  Sun  a  flat  surface.  The  point  whose  codeclination  is 
considered  then  becomes 


where  6  =  the  angle  from  the  pole  of  the  ecliptic  toward 
its  equator ; 

and  tan(23°.5-*). 

tan  23°. 5 

Something  is  omitted  by  this  process  because  the  visible 
zone  really  descends  lower  at  the  sides  than  in  the  centre, 
but  on  the  other  hand  the  effect  on  the  tropical  belt  of  the 
Earth  is  relatively  greater  than  on  the  polar  ones  because 
of  the  less  distance  of  the  centre  of  the  Sun.  The  result 
is  to  understate  the  case  against  the  supposed  paleozoic 
Sun  and  thus  to  increase  the  force  of  the  reasoning. 

From  the  table  it  appears  that  the  climate  in  the  polar 
regions  would  be  unaffected  in  midwinter  and  midsummer, 
the  only  seasonal  difference  being  that  spring  would  come 


NOTES 


235 


on  somewhat  earlier  than  now.     Thus  the  seasons  would 
still  exist  and  the  polar  climate  not  be  tropical  at  all. 

The  heat  due  the  insolation  at  the  equator  at  the  equinox 
is  taken  as  unity  in  both  cases  because  no  greater  heat 
there  is  to  be  accounted  for  then  than  now. 


INSOLATION 

Equator  at  Equinox  =  i.oo  in  both  cases. 


LATITUDE 

EFFECTIVE  DECLINA- 
TION OF  SUN 

INSOLATION  PALEOZOIC 

SUN 

INSOLATION  PRESENT 

SUN 

N. 

S. 

MIDWINTER 

90 

0 

o.oo 

0.00 

82 

4-6 

o.oo 

0.00 

66.5 

13.0 

0.06 

0.00 

5° 

21.  1 

0.21 

0.19 

40 

23-5 

o-3S 

o-3S 

3° 

23-5 

0.51 

0.51 

20 

23-5 

0.66 

0.66 

EQUINOX 

N. 

90 

10-5 

0.29 

o.oo 

82 

6-3 

0.25 

0.14 

66.5 

o.o 

0.40 

0.40 

5° 

o.o 

0.64 

0.64 

40 

o.o 

0.77 

0.77 

30 

o.o 

0.87 

0.87 

20 

0.0 

0.94 

0.94 

MIDSUMMER 

90 

23-5 

I.2S 

.25 

82 

23-5 

1.24 

.24 

66.5 

23-5 

I.I5- 

.15- 

5°, 

23-5 

I.I5 

•1S 

40 

23-5 

I.I5+ 

•1S+ 

30 

23-5 

I-I3 

•13 

20 

23.5 

1.09 

1.09 

236      MARS   AS   THE   ABODE   OF   LIFE 


10 

ON  THE   INFLUENCE  UPON  THE  CLIMATE  OF   CARBON 
DIOXIDE  IN  THE  AIR 

From  some  careful  and  elaborate  calculations  of  Profes- 
sor Arrhenius  it  appears  that  an  increase  of  carbonic  acid 
in  our  air  to  thrice  its  present  amount  would  raise  the  tem- 
perature as  follows : 

CARBONIC  ACID  =  3 
INCREASE  IN  TEMPERATURE  OVER  CARBONIC  ACID  =  i 


LATITUDE 

DBC.-FEB. 

MARCH-MAY 

JUNB-AUG. 

SEPT.-NOV. 

YEAR 

70-60 
50-40 
3O-2O 

+  9.1  C. 

+  9-5 
+  8.7 

+  9-3  C. 
+  94 

+  8.3 

+  94  C. 
+  8.6 

+  7-5 

+  94  C. 
+  9-2 
+  7-9 

+  9-3  C. 

+  9-2 
+  8.1 

1  0-0 

+  74 

+  7-3 

+  7-2 

+  7-5 

+  7-3 

We  shall  assume  these  figures  to  be  correct  and  combine 
with  them  a  table  showing  the  present  temperature  at 
different  latitudes  in  every  month  taken  by  him  from 
Dr.  Buchan  and  here  abbreviated. 

CARBONIC  ACID  =  i 


LATITUDE 

DEC.-FEB. 

MARCH-MAY 

JUNE-AUG. 

SEPT.-NOV. 

YEAR 

0 

70-60 

-2I.I  C. 

-    8.3  C. 

+    7-5  C. 

-    6.0  C. 

-    7.0  C. 

50-40 

-     1-4 

+  7.8 

+  18.7 

+    9-7 

+     8.7 

30-20 

+  17.0 

+  21.5 

+  26.0 

+  23.0 

+  21.9 

10-0 

+  25.5 

+  25.8 

+  25.4 

+  25.5 

+  25.5 

From  these  two  tables  it  appears  that  the  increase  of 
temperature  from  increase  of  carbon  dioxide  in  the  air  from 


NOTES 


237 


i  to  3  would  be  only  two  degrees  centigrade  greater  at  65°  N. 
than  at  the  equator ;  the  mean  for  the  year  at  the  upper 
latitude  being  still  only  +  2°.3  C.  while  it  would  be  32°.8  C. 
at  latitude  5°  N.  In  the  second  place  the  seasons  in  the 
polar  regions  would  remain  substantially  what  they  are 
now.  For  at  latitude  7O°-6o°  we  should  have  : 

TEMPERATURE  WITH  CARBONIC  ACID  =  3 


LATITUDE 

DEC.-FKB. 

MARCH-MAY 

JUNE-AUG. 

SEPT.-NOV. 

0 

70-60  N. 

-  12.0  C. 

+  1.0  C. 

+  16.9  C. 

0 

+  3-4  C. 

Such  cold  in  winter  would  be  prohibitive  to  tropic  vege- 
tation, and  polyp  corals  could  certainly  not  flourish  on  it 
seventeen  degrees  still  farther  north  toward  the  pole. 


EFFECT  OF  INCREASED  CARBON  DIOXIDE  UPON  PLANTS 

Quite  apart  from  the  question  of  warmth  it  by  no 
means  follows  that  an  increase  of  carbon  dioxide  in  the  air 
to  three  or  four  times  its  present  amount  would  conduce 
to  vegetation.  With  common  plants  and  under  otherwise 
present  normal  conditions  it  certainly  does  not.  To  de- 
termine what  effect  upon  plants  a  greater  percentage  of 
it  than  the  present  one  would  have,  careful  experiments 
were  performed  in  1902  by  Dr.  Horace  T.  Brown,  LL.D., 
F.R.S.,  and  Mr.  F.  Escombe,  B.Sc.,  F.L.S.*  The  plants 
selected  were  ordinary  flowering  plants  or  angiosperms. 
They  found  that  an  increase  of  carbonic  acid  in  the  at- 
mospliere  to  11.4  parts  in  10,000  from  the  normal  amount 
of  2.8  to  3  not  only  hurt  the  growth  of  the  plants  but  pre- 


*  Proceedings  of  the  Royal  Society,  1902,  Vol.  LXX. 


238      MARS   AS   THE   ABODE   OF   LIFE 

vented  reproduction.  The  plants  became  sickly  and  were 
unable  to  flower  and  seed.  The  experiment,  of  course, 
does  not  show  that  a  different  effect  might  not  be  pro- 
duced on  cryptogams  such  as  constituted  the  flora  of  Car- 
boniferous times,  nor  does  it  demonstrate  that  with  time 
enough  adaptation  to  such  changed  surroundings  might 
not  result  in  a  positive  gain  to  the  plants  concerned ;  but  it 
certainly  affords  no  evidence  in  favor  of  either  supposition. 

ii 

ATMOSPHERE  OF  MARS 

Amount.  —  Of  the  amount  of  the  Martian  atmosphere 
we  have  no  certain  knowledge.  From  its  effects  we  know 
that  such  an  atmosphere  exists  and  these  effects  are  com- 
patible with  an  air  thinner  than  our  own.  With  regard 
to  its  density  the  best  determination  at  present  is  to  be 
got  from  the  planet's  albedo,  the  albedo  of  a  body  being 
its  intrinsic  brightness.  Now  from  the  albedo  of  various 
rocks,  of  forests,  and  of  snow,  and  from  the  relative 
amounts  of  each  that  appear  upon  the  Martian  disk,  we 
may  calculate,  taken  in  connection  with  the  whole  albedo 
of  the  planet,  the  proportionate  albedoes  of  its  surface 
and  its  air.  Nearly  five-eighths  of  the  surface  is  desert 
which  has  an  albedo  of  about  .16,  three-eighths  a  blue-green 
with  an  albedo  of  .07,  while  less  than  one-sixth  is  of  a 
glistening  white  of  roughly  .75.  These  would  combine  to 
give  an  albedo  of  .13.  This,  however,  is  illuminated  by 
so  much  only  of  sunlight  as  penetrates  the  air,  about  three- 
quarters  of  the  whole.  Whence  the  apparent  albedo  of 
the  surface  seen  from  without  must  be  .10.  Now  as  the 
total  albedo  of  the  planet  is  .27,  and  .10  is  from  the  sur- 
face, the  remaining  .17  must  be  the  albedo  of  the  air. 

Assuming  the  densities  of  the  mundane  and  of  the 
Martian  atmospheres  to  be  proportionate  to  their  brilliancy, 


NOTES  239 

or  as  75  to  17,  which  would  seem  something  like  the  fact, 
since  the  denser  the  air  the  more  dust  it  would  buoy  up, 
and  it  is  chiefly  by  what  it  holds  in  suspension  that  we  see 
it,  we  have  for  the  Martian  air  a  density  about  two-ninths 
of  our  own  over  each  square  unit  of  surface. 

But,  if  the  original  mass  of  air  on  each  planet  was  as 
that  planet's  mass,  we  should  have  for  the  initial  amounts 
9.3  for  the  Earth  to  i.o  for  Mars.  This  would  be  dis- 
tributed as  their  respective  surfaces,  or  in  the  ratio  of  79 192 
to  422O2,  or  as  3.5  to  i ;  which  would  give  2.7  times  as 
much  air  for  the  Earth  per  unit  of  surface.  The  differ- 
ence between  —  and  — ,  or  the  amount  the  albedo  im- 
2.7  4.5 

plies  now  present  and  the  amount  the  planet  would  have 
had,  assuming  proportionate  masses  to  start  with,  may  per- 
haps be  attributed  to  the  greater  relative  loss  of  air  Mars 
has  sustained  because  of  parting  more  quickly  with  its  air 
envelope. 

Surface  density  of  its  air.  —  To  get  the  density  of  the 
Martian  air  at  the  surface  of  the  planet,  which  is  of  course 
a  very  different  thing  from  the  amount  of  air  above  that 
surface,  we  must  divide  the  amount  by  the  relative  gravity 
there.  For  the  density  of  an  atmosphere  at  any  height 
being  proportionate  to  its  own  decrease  —  if  the  density  be 
taken  as  proportional  to  the  pressure,  which  is  practically 
true  for  gases  at  the  atmospheric  pressures  considered,  and 
if  the  temperature  be  considered  constant  —  then  if  D 
denote  the  density  at  any  point, 

dD  =  -  Dg  -  dx, 

where  g  denotes  the  force  of  gravity  at  the  surface  of 
the  Earth  and  is  constant  for  the  distance  concerned,  and 
x  is  reckoned  outward  from  the  surface. 

Whence  D  =  Ae~gxt 

A  being  the  density  at  the  surface. 


240      MARS   AS   THE   ABODE   OF   LIFE 

Correspondingly,  we  have  for  Mars 


Al  being  the  density  of  its  air  at  its  surface  and^  gravity 
there.  For  the  whole  mass  of  air  over  a  given  point  we 
have  for  the  Earth 


and  similarly  for  Mars 


Taking  g=  I  and  therefore  g^  =  .38,  we  have,  since  the 
whole  mass  of  air  above  a  point  on  Earth  is  4.5  what  it  is 
on  Mars, 

A=^' 

Whence  as  A  =  30  inches  or  760  'mm.  barometric  pressure, 
A1  =  2.5  inches,  or  64  mm. 

12 

THE  MEAN  TEMPERATURE  OF  MARS 
DIVISION  OF  RADIANT  ENERGY 

So  soon  as  a  radiant  ray  strikes  matter  it  suffers  division 
of  its  energy.  Part  of  it  is  reflected,  part  absorbed,  and 
part  transmitted.  What  is  reflected  is  sent  off  again  into 
space,  performing  no  work  in  the  way  of  heating  the  body. 
Now  the  amount  reflected  is  not  the  same  in  all  cases,  de- 
pending for  its  proportion  upon  the  character  of  the  matter 
the  ray  strikes. 

If  the  surface  of  a  planet  be  itself  exposed  unblanketed 
by  air,  the  absorbed  and  transmitted  portions  go  to  heat 
the  planet,  directly  or  indirectly. 


NOTES  241 

If  the  planet  be  surrounded  by  air,  the  portion  trans- 
mitted by  this  air,  plus  what  is  radiated  or  reflected  from 
it  to  the  solid  surface,  must  first  be  considered.  Then, 
upon  this  quota  as  a  basis,  must  secondly  be  determined 
how  much  the  surface  in  its  turn  reflects.  The  balance 
alone  goes  to  warm  the  ground  or  ocean. 


LIGHT  AND  HEAT 

Radiant  energy  is  light,  heat,  or  actinism,  merely  accord- 
ing to  the  effect  we  take  note  of.  If  our  eyes  were  sensi- 
tive equally  to  all  wave-lengths,  we  could  gauge  the  amount 
of  heat  eceived  by  a  body  by  the  amount  of  light  it  re- 
flected, —  that  is,  by  its  intrinsic  brightness,  or  albedo. 
For  this  percentage  deducted  from  unity  would  leave  the 
percentage  of  heat  received.  This  procedure  may  still  be 
applied,  provided  account  be  also  taken  of  the  heat  deple- 
tion suffered  by  the  invisible  rays.  Two  problems,  then, 
confront  us. 

We  must  find  the  albedoes  of  the  several  planets  in 
order  to  compare  one  with  another  in  its  reception  of  heat, 
and  we  must  find  the  relation  borne  by  the  visible  and  in- 
visible rays  to  the  subject.  The  latter  problem  may  best 
be  attacked  first. 

Actinometers  and  pyrheliometers  are  instruments  for 
measuring  in  toto  the  heat  received  from  the  Sun ;  and 
they  have  been  used  by  Violle,  Crova,  Hansky,  and  others 
to  the  determination  of  this  quantity  at  given  places,  and 
so  to  a  conclusion  as  to  the  amount  of  heat  outside  our  air, 
or  the  Solar  Constant.  Langley's  great  contribution  to  the 
subject  was  the  pointing  out  that  the  several  wave-lengths 
of  the  different  rays  were  not  of  homogeneous  action  or 
modification,  and  that  to  an  exact  determination  of  the 
Solar  Constant  it  is  necessary  to  consider  the  action  of 


242     MARS   AS  THE   ABODE  OF  LIFE 

each  separately,  and  then  to  sum  them  together.  To  this 
end  he  invented  his  spectro-bolometer. 

By  means  of  this  instrument  Langley  mapped  the  solar 
radiation  to  an  extension  of  the  heat  spectrum  unsuspected 
before.  He  then  carried  it  up  Mt.  Whitney  in  California,  and 
discovered  two  important  facts  :  one,  that  the  loss  in  the  visi- 
ble part  of  the  spectrum  was  much  greater,  not  only  actually, 
but  relatively  to  the  rest,  than  had  been  supposed ;  and  the 
other,  that  the  greater  the  altitude  at  which  the  observations 
were  made,  the  larger  the  value  obtained  for  the  Solar  Con- 
stant. Both  of  these  are  pertinent  to  our  present  inquiry. 

With  a  rock-salt  prism,  instead  of  a  glass  one,  he  next 
extended  still  farther  the  limits  of  the  heat  spectrum  toward 
the  red,  the  effect  of  the  solar  radiation  proving  not  neg- 
ligible as  far  as  X  =  15/4. 

In  1901  Professor  Very,  who  had  been  his  assistant 
earlier,  published  an  important  memoir  on  the  Solar  Con- 
stant, based  upon  these  bolometric  observations,  but  with 
a  value  for  it  got  from  spectral  curves  derived  from  simul- 
taneous actinometric  and  bolometric  determinations  at 
Camp  Whitney  and  Lone  Pine,  and  extended  from  them 
outside  the  atmosphere  by  taking  both  air  and  dust  effects 
into  account  in  selectively  reflecting  and  diffracting  the 
energy  waves.  The  air  effect  is  proportionate  to  the  air 
mass,  but  the  dust  effect  increases  in  greater  ratio  as  one 
nears  the  surface  of  the  ground.  The  formulae  he  used 
were  adaptations  of  those  by  Rayleigh  for  accounting  for 
the  selective  reflection  and  diffraction  of  small  particles.* 

ENERGY  OF  VISIBLE  AND  INVISIBLE  SPECTRUM 

Planimetrical  measurement  of  the  area  enclosed  by  the 
curve  deduced  for  outside  our  atmosphere  gives  the  follow- 
ing results : 

*  U.  S.  Department  of  Agriculture,  Weather  Bureau,  No.  254. 


NOTES 

DISTRIBUTION  OF  HEAT  IN  THE  SPECTRUM 


243 


WAVE-LENGTHS 

PERCENTAGE 

Invisible       

X  —  O.2  U—  O.^Q^  u 

2.C 

Visible 

A  —  o  76  u  I  c.  u 

6c  c 

100. 

giving  for  the 
of  the  whole. 


Visible  portion,      32  per  cent, 
Invisible  portion,  68  per  cent, 


Loss  OF  HEAT  IN  TRAVERSE  OF  THE  AIR 

Turning,  now,  from  the  question  of  the  initial  heat  for 
different  parts  of  the  spectrum  at  the  time  the  solar  radia- 
tion enters  the  air,  we  come  next  to  consider  the  loss  the 
several  rays  sustain  in  their  traverse  of  it. 

From  Very's  curves  for  the  radiation  at  the  confines  of 
the  atmosphere  at  Camp  Whitney  and  at  Lone  Pine, 
1 8  X  =  1.2  p,  we  get  the  amount  transmitted  at  these  two 
stations,  employing  planimetric  measurement  as  before, 
and  introducing  with  him  the  absorption  in  the  red  and 
infra-red  from  the  Alleghany  measures,  which  he  considers 
the  same  at  Lone  Pine. 

From  Very's  measures  we  have,  calling  the  whole  heat 
at  the  confines  of  the  atmosphere  unity,  — 

TRANSMISSION 


A=0.2   H-I.2   ,1 

A=i.aj*-i5/u. 

Outsidfi 

CO 

CQ 

Camp  Whitney      
Lone  Pine     ...          

31-3 

24.  "* 

2C.I 

244      MARS   AS   THE   ABODE   OF   LIFE 


To  get  that  for  sea-level  we  shall  take  Crova's  actinometric 
measures  at  Montpellier  (height  40  m.),  made  on  August 
13,  1888,  at  i2h3Om,  under  a  barometer  of  761  mm.  Simul- 
taneously with  these,  other  self -registering  ones  were  taken 
by  him  on  Mt.  Ventoux  (height  2000  m.).  The  respective 
calories  he  obtained  were,  — 


MONTPELLIER 

Mr.  VENTOUX 

Aug.  13,  I2l>  30m,  1888    .      .      . 

i 
0.975  calory, 
bar.  761.1  mm. 

1.360  calories, 
bar.  613.5  mm- 

We  shall  reduce  these  to  the  same  scale  as  the  Lone 
Pine  results,  made  with  the  pyrheliometer  and  used  by 
Very,  to  wit :  — 

Aug.  II,  12,  14,  I2h-I2h  30m,  l88l. 

giving  for 


LONE  PINE 
:-533  calories,  bar.  663  mm. 


MONTPELLIER 

1.180  calories 


MT.  VENTOUX 
1.643  calories 


This  value  of  1.180  is  one  which  is  probably  about  the 
average  of  clear  days  in  our  latitude,  the  day  in  question 
being  registered  by  Crova  as  "very  clear." 

From  these  several  data  we  find  the  following  values 
for  the  solar  radiation  received  at  the  respective  posts,  in 
calories  in  one  column,  in  percentage  of  that  entering  the 
atmosphere  in  another. 

SOLAR  RADIATION 


BAR. 

CALORIES 

PERCENTAGE 

Outside  the  atmosphere  .     . 
Camp  Whitney  

o 

3.127 

1.  806 

I.OOO 
.606 

Lone  Pine      

663  mm. 

I.C-57 

•49° 

Montpellier   

761  mm. 

1.180 

•377 

NOTES  245 

The  loss  in  the  visible  spectrum  is  almost  wholly  from 
selective  or  general  reflection  and  from  diffraction,  that  in 
the  invisible  one  from  selective  absorption.  The  absorp- 
tive loss  by  bands  in  the  former  is  only  about  I  per  cent 
of  the  whole,  and  the  loss  by  reflection  in  the  latter  prob- 
ably not  over  7  per  cent  of  its  depletion. 

In  view  of  the  fact  that  the  absorption  is  known  to  take 
place  high  up  in  the  air,  Very  adopted  the  Alleghany 
amount  for  Lone  Pine,  the  difference  being  insensible; 
but  when  it  comes  to  Camp  Whitney  it  is  clear  from  the 
above  that  9  per  cent  of  it  is  got  rid  of  between  X  =  1.2  n 
and  =  10  fj.  by  rising  the  11,700  ft.  from  sea-level. 

DEPLETION  IN  VISIBLE  RAYS 

We  may  now  find  the  depletion  in  the  visible  part  of  the 
spectrum  which  is  not  in  general  the  same  as  that  for  the 
invisible  part,  decreasing  relatively  with  the  altitude  and 
reversely  increasing  as  the  air  envelope  becomes  thicker. 
It  does  this  at  a  greater  rate  than  the  increase  of  the  air 
mass,  because  the  particles  suspended  in  the  air — dust, 
water  globules,  and  ice  —  augment  more  rapidly  than  the  air 
mass  as  one  approaches  the  ground. 

Drawing  the  curve  for  transmission  at  the  sea-level  on 
the  same  principles  as  those  for  outside  the  atmosphere  at 
Camp  Whitney  and  at  Lone  Pine,  and  then  measuring  the 
amounts  of  transmission  of  each  within  the  limits  of  the 
visual  rays,  from  X  =  .393  /A  the  K  line  to  X  =  .76  /u, 
the  A  band,  we  get  the  following  table :  — 


246     MARS   AS  THE   ABODE   OF  LIFE 

TRANSMISSION  OF  SOLAR  RADIATION  IN  THE  VISIBLE  SPECTRUM 


CALORIES  RECEIVED 

FROM  THE 

WHOLE  SPECTRUM 

VISIBLE  PORTION 
TRANSMITTED 

Outside  the  atmosphere      .     . 
Camp  Whitney 

3.127 
1.  806 

I.OOO 

.664 

Lone  Pine     
Sea-level 

1-533 
1.180 

.482 

.210 

The    relative    loss    in    the    regions    I,   X  =  .393  n    to 

X  =  .76/t,   and   II,  X=.76/*  to  X  =1.2/4,  between  the 
several  stations  is  as  follows:  — 

i  ii 

Outside  to  Camp  Whitney 0.105  0.029 

Camp  Whitney  to  Lone  Pine    ....    0.055  o.oio 

Lone  Pine  to  sea-level 0.086  0.027 


LIGHT  RECEIVED  FROM  THE  DAY  SKY 

To  these  transmissions  must  be  added  that  part  of  the 
solar  radiation  which  is  lost  by  reflection  and  diffraction 
in  the  atmosphere  before  reaching  the  ground,  but  is  re- 
flected again  upon  it,  causing  the  brightness  of  the  day 
sky.  This  amount  is  sufficient  to  obliterate  the  stars. 
Compared  with  direct  sunlight,  its  ratio  as  determined  by 
Langley  *  is 


Illumination 


SUN 
80 


SKY 


or  24  per  cent  of  the  sun's  light. 

We  must  therefore  increase  the  energy  transmitted  by 
24  per  cent  of  itself.     This  gives  finally  :  — 


'Professional  Papers  of  the  Signal  Service,"  Vol.  15. 


NOTES 


247 


TRANSMISSION 

PORTIONS  REFLECTED 
INTO  SPACE 

Outside        .... 

I.OO 

IOO 

o 

Sea-level      .... 

0.21 

26 

74 

ALBEDO  OF  THE  EARTH 

Now  the  fraction  of  the  incident  energy  in  the  visible 
spectrum  is  that  by  which  we  see  the  body  and  is  called 
its  albedo.  The  albedo  of  our  air,  then,  comes  out  .74. 
To  get  the  whole  albedo  of  the  Earth  we  must  add  to  it 
the  albedo  of  the  surface. 

The  albedo  of  various  rocks  and  of  the  ocean  is  as 
follows : 


White  quartzite    .     .    0.25  Dark  slate    . 

Clay  shale    .    .    .    .    0.16  Ocean      .    . 

For  forest  we  may  perhaps  take      .    0.07 
and  snow  according  to  purity     .    .    0.50-0.78 


0.09 
0.075 


The  percentages  of  distribution  of  surfaces  being  about 

Ocean  ....  72  per  cent  Steppes  and  desert  .  10  per  cent 
Forest  .  .  .  .  10  per  cent  Polar  caps  ....  6  per  cent 

we  deduce  n  for  the  albedo  of  the  surface.  But  this 
being  illuminated  by  only  25  per  cent  of  the  light  outside 
the  air  gives  about  3  for  its  quota  to  the  planet's  illumina- 
tion. When  finally  the  Earth's  whole  albedo  to  one  view- 
ing it  from  space  becomes  .74  +  .03  =  .77  albedo  of  the 
Earth  for  a  clear  sky. 

As  the  Earth's  is  about  50  per  cent  cloud-covered  (see 
the  researches  of  Teisserenc  de  Bort  on  Nebulosity)  and 
the  albedo  of  cloud  is  .72,  we  get  .75  for  the  mean  albedo 
of  the  Earth. 


248      MARS   AS   THE   ABODE   OF   LIFE 

VALUE  OF  Loss  OF  LIGHT  A  MINIMAL  ONE 

That  the  value  above  found  for  the  percentage  trans- 
mission of  solar  radiation  to  the  Earth's  surface  is  a  maxi- 
mal rather  than  a  minimal  amount,  and  the  albedo  a 
minimal  rather  than  a  maximal  one,  is  hinted  by  the  fact 
that  the  higher  the  observer  ascends  above  the  surface, 
the  greater  his  estimate  of  the  solar  constant  becomes. 
Thus  Langley  in  his  memoir  on  the  Mt.  Whitney  expedi- 
tion says : — 

"  In  accordance  with  the  results  of  previous  observers, 
then,  and  of  our  own  with  other  instruments,  we  find  a 
larger  value  for  the  Solar  Constant  as  we  deduce  it  from 
observations  through  a  smaller  air  mass."  The  italics  are 
his.* 

DEPLETION  BY  WATER-VAPOR  ON  MARS 

We  are  now  in  position  to  estimate  the  heat  actually 
received  respectively  at  the  surfaces  of  Mars  and  the 
Earth.  The  visual  part  of  the  spectrum  containing  32  per 
cent  of  the  incident  solar  radiation  gives  us  its  quota  di- 
rectly from  the  albedo,  since  the  heat  received  =  I  albedo. 
The  infra-red  portion  containing  65  per  cent  of  the  whole 
depends  upon  the  character  of  the  air  and  of  what  it  holds 
in  suspension.  The  greater  bulk  of  the  depletion  in  this 
part  of  the  spectrum  comes  from  the  absorption  by  water- 
vapor,  water  itself,  or  ice  and  carbon  dioxide.  At  the 
Earth's  surface  the  transmission  in  consequence  is  about 
50  per  cent ;  at  Camp  Whitney  it  was  about  59  per  cent. 
We  might,  therefore,  suppose  it  still  greater  through  the 
air  of  Mars,  which  is  very  thin,  and  if  we  did  so  we  should 
find  a  still  larger  fraction  of  solar  heat  to  be  received  by 
the  planet's  surface ;  so  that  such  a  supposition  would 
actually  increase  the  cogency  of  the  present  argument. 

*  "  Researches  on  Solar  Heat,"  p.  68. 


NOTES  249 

But  the  very  thinness  of  the  air  joined  to  the  lesser  gravity 
at  the  surface  of  the  planet  would  lower  the  boiling-point 
of  water  to  something  like  110°  F.  The  sublimation  at 
lower  temperatures  would  be  correspondingly  increased. 
Consequently  the  amount  of  water-vapor  in  the  Martian 
air  must  on  that  score  be  relatively  greater  than  in  our 
own. 

DEPLETION  BY  CARBON  DIOXIDE 

Carbon  dioxide,  because  of  its  greater  specific  gravity, 
would  also  be  in  relatively  greater  amount,  so  far  as  that 
cause  is  considered.  For  the  planet  would  part,  cceteris 
paribus,  with  its  lighter  gases  the  quickest. 

Whence,  as  regards  both  water-vapor  and  carbon 
dioxide  we  have  reason  to  think  them  in  relatively  greater 
quantity  than  in  our  own  air  at  corresponding  barometric 
pressure.  We  may  therefore  assume  provisionally  that 
the  absorption  due  this  cause  is  what  it  is  with  us  at 
Camp  Whitney,  or  about  40  per  cent  of  the  whole,  leaving 
60  per  cent  of  the  heat  transmitted. 

It  is  distinctly  to  be  noted  that  though  this  estimate 
lowers  the  determination  of  the  heat  received  at  the  sur- 
face of  Mars,  what  is  thus  lost  in  reception  goes  to  make 
the  retention  of  the  heat  received  all  the  greater. 

ALBEDOES  OF  THE  PLANETS 

The  albedoes  of  the  several  planets,  according  to  the 
latest  determinations,  those  by  Miiller  at  Potsdam,  together 
with  that  found  above  for  the  Earth  and  that  obtained  for 
the  Moon  by  Zollner,  stand  thus  :  — 


Mercury  . 

.     0.17 

Jupiter  . 

.    0.75  f  (using  Struve's 

Venus.    . 

.     0.92 

Saturn  . 

.     0.88  j   latest  diametral 

Earth  .     . 

.     0.75 

Uranus  . 

.    0.73  [  measures,  .78) 

Moon  .     . 

.    0.17  (Zollner) 

Neptune 

.    0.63 

Mars   .     . 

.    0.27 

250      MARS   AS   THE   ABODE   OF   LIFE 


HEAT  RECEIVED  BY  EARTH  AND  MARS 
We  will  now  apply  the  argument  from  the  albedo. 

HEAT  RECEIVED  AT  THE  SURFACES  OF  MARS  AND  THE  EARTH 


PER  CENT  OF 
WHOLE  ENERGY 

PER  CENT  OF  HEAT  RE- 
CEIVED TO  WHOLE  ENERGY 

Mars 

Earth 

Visual  spectrum       .... 
Infra-red    

32 
65 

73 
60 
64 

23 

5£_ 
41.5 

Total 

The  ultra-violet  rays  slightly  increase  the  depletion  by 
selective  dispersion  for  both  planets,  and  probably  the 
more  for  Mars. 

INSOLATION 

But  this  is  not  all.  The  above  deduction  applies  only 
to  such  sky  as  is  clear.  Now  the  Earth  is  cloud-covered 
to  the  extent  of  50  per  cent  of  its  surface  on  the  average ; 
Mars,  except  for  about  six  Martian  weeks,  at  the  time  of 
the  melting  of  the  polar  cap  and  over  an  area  extending 
some  fifteen  degrees  from  the  pole,  stands  perpetually 
unveiled.  The  surface  thus  fog-enveloped  is  .034  of  its 
hemisphere,  and  the  time  .23  per  cent  of  the  half  year, 
whence  the  total  ratio  of  cloud  to  clear  the  whole  year 
through  over  the  whole  surface  is  less  than  i  per  cent. 

The  albedo  of  cloud  being  .72,  its  transmission,  includ- 
ing absorption  re-given  out,  cannot  exceed  .28  for  the  visi- 
ble spectrum,  and  may  be  taken  as  .20  for  the  whole.* 
Consequently  the  effective  heat  received  on  this  score  by 

*  This  agrees  with  Arrhenius'  estimate  of  the  heat  transmissibility  of  cloud. 


NOTES  251 

the  Earth  is  about  as  .20  x  .504-  i.oo  x  .50=  .60,  and  for 
Mars  .99,  giving  the  ratio  between  the  two  planets  that 
of  .60  to  .99. 

Taking  now  Stefan's  law  that  the  radiation  of  a  body 
is  as  the  fourth  power  of  its  temperature,  and  remember- 
ing that,  since  the  two  planets  maintain  their  respective 
mean  annual  temperatures,  they  must  radiate  as  much 
heat  as  they  receive,  we  have  the  following  equation 
from  which  to  find  the  mean  annual  temperature  of  Mars, 
x,  in  which  459.4° +  60°  or  519.4°  F.  on  the  absolute 
scale  denotes  the  mean  annual  temperature  of  the 
Earth :  — 

x\  519.4° ::  (/i2  x  .64  x  .99  :  \/i.5242  x  .415  x  .60 

or  *=  5I940  Iff, 

giving  ^=531.4°  Abs.  =72°  F.  or  22°  C. 

HEAT  RECEIVED  AND  HEAT  RETAINED 

Such,  then,  would  be  the  mean  annual  temperature  of 
the  planet,  were  the  heat  retained  as  well  there  as  here. 
I  am  far  from  saying  that  such  is  the  temperature.  For 
the  retention  is  not  the  same  on  the  two  planets,  being,  on 
account  of  its  denser  air,  much  better  on  the  Earth.  But 
that  such  is  the  amount  received  is  enough  to  suggest 
very  different  ideas  as  to  the  climatic  warmth  from  those 
hitherto  entertained. 


TEMPERATURE  DEDUCED  FROM  HEAT  RETAINED 

To  obtain  some  idea  of  the  heat  retained  and  of  the 
temperature  in  consequence  we  may  proceed  in  this  way : 
Let  y  =  the  radiant  energy  received  at  the  surface  of  the 
Earth. 


252      MARS   AS   THE   ABODE   OF   LIFE 

jj  =  that  similarly  received  on  Mars. 

e  =  the  relative  emissivity  or  the  coefficient  of  radia- 
tion from  the  surface  of  the  Earth,  giving  the 
ratio  of  the  loss  in  twenty-four  hours  to  the 
amount  received  in  the  same  time,  due  to 
factors  other  than  the  transmissibility  of  the 
air,  which  is  separately  considered. 

*!  =  the  same  coefficient  for  Mars. 

Clouds  transmit  approximately  20  per  cent  of  the  heat 
reaching  them;  a  clear  sky  at  sea-level,  50  per  cent. 
Consequently  as  the  sky  is  half  the  time  cloudy,  the  mean 
transmission  through  its  air  envelope  for  the  Earth  is 


For  Mars  it  is 

To  get,  then,  the  mean  temperature  of  the  planet  in 
degrees,  x,  from  the  heat  retained,  which  is  the  daily 
mean  receipt  less  the  mean  loss,  we  have  the  follow- 
ing equation,  the  mean  temperature  of  the  Earth  being 
[519.4°  F.  Abs.]  288°  C.  above  absolute  zero:— 


288.5       VXi  -  -35  e) 

DETERMINATION  OF  e 

To  find  e  we  have  the  data  that  the  fall  in  temperature 
toward  morning  on  the  Earth  under  a  clear  night  sky  is 
about  1  8°  F.  or  10°  C.  ;  under  a  cloudy  one,  about  7°  F. 
or  4°  C.  Taking  the  average  day  temperature  from  these 
data  at  292°  Abs.  on  the  centigrade  scale,  or  19°  C.,  and 
considering  an  average  day  sky  and  a  clear  night,  we  have 
the  transmission  or  loss 

K-35  +  .50)*  or  .425*; 


NOTES  253 

while  for  an  average  day  and  a  cloudy  night  it  is 

K-35  +  -20>  or  .275  e. 
We  form  the  following  equation  to  determine  e :  — 


292°  —  10°  =  V  X  i  —  -425  e) 
292°  -  4°       ty(i--275*)f 
whence  e  =  .47. 

Since  the  radiation  by  day  is  greater  by  about  1.15  than 

by  night,  being  as 

we  have  more  approximately 

J(.40+.so>or  .45  * 
for  a  clear  night  and  average  day  and 

J{.40  +  .20>  or  .30  * 

for  a  cloudy  night  under  the  same  conditions. 
This  gives  e  —  .46, 

or  substantially  what  it  was  before.  It  changes  the  final 
result  for  the  mean  temperature  of  Mars  by  less  than  two- 
tenths  of  a  degree. 

DETERMINATION  OF  el 

Since  in  the  mean  the  planet  radiates  as  much  heat  as  it 
receives  and 

f =<•'<>. 

the  radiation  must  be  in  the  same  ratio.  Whence,  the  loss 
by  radiation  in  twenty-four  hours  on  Mars,  so  far  as  it 
depends  on  the  heat  received,  is 

e  =  i.i  e 


254      MARS   AS   THE   ABODE   OF   LIFE 

or  by  the  more  approximate  calculation  in  the  paragraph 
above,  it  still 

=  .51. 

Substituting  these  values  in  our  equation  (page  250),  we 
find  x>  the  mean  temperature  of  Mars, 

=  8°.7C. 
or  =  470.7  R, 

taking  into  account  the  heat  radiated  away  as  well  as  the 
heat  received  and  gauging  the  temperature  by  the  heat 
retained ;  by  the  net,  instead  of  the  gross,  amount  of  the 
radiant  energy  received. 

If  we  assume  clouds  to  transmit  less  heat  than  20  per 
cent,  we  diminish  y  and  increase  (i  —  -35^),  so  that  the 
ultimate  result  is  not  greatly  altered. 

If  we  take  Arrhenius1  formula  for  the  temperature  T  of  the  Earth's 
surface  as  affected  by  the  air-envelope,  we  have  as  determined  in  his 
paper  on  the  effect  of  carbon  dioxide  in  the  air :  — 


-  a)A(l  +  v)  + 

r*  = 


y(i  +  v  -  0v) 
where       a  =  atmospheric  absorption  for  solar  heat, 

/3  =  atmospheric  absorption  for  earth-surface  heat, 
A  =  Solar  Constant,  less  loss  by  selective  reflection  by  the  air, 
M  -  heat  conveyed  to  the  air  from  other  points, 
N  =  heat  conveyed  to  the  surface  from  other  points, 
v  =  I  —  albedo  of  the  surface, 
y  =  radiation  constant. 

The  values  for  these  quantities  found  bolometrically  for  a  clear  sky 
are  a  =  .50, 

A  =  i  —  .79  x  .32  =  .747  =  whole  spectrum  —  albedo  of  the  air  x 

visible  portion, 
/?  =  a  approximately, 


NOTES  255 

For  the  Earth  in  its  entirety  M  =  o  and  IV  =o,  since  what  is  lost  by  con- 
vection in  one  place  is  gained  in  another. 

Applying  this  same  formula  to  the  case  of  Mars,  we  have  similarly 

ttj  =  .40  approximately, 

Al  =  —  -  —  -  (i  —  .17  x  .32)  =  whole  spectrum  —  albedo  of  its  air  x 

visible  portion 

=  ^246. 
1.5242 

/?!  =  ttj  approximately. 
v,  =  i  -  .13  =  .87. 
Whence  for  the  Earth  under  a  clear  sky 

T4  _  A(i  +  v  -  vet) 
y(i  +  v  -  PV)' 

and  similarly  for  Mars,  substituting  its  values  for  A,  a,  and  /8. 

Since  in  both  a  =  /3  and  yt  =  y  approximately,  we  have  for  7\  for  Mars, 


But  the  Earth  is  .50  cloud-covered,  and  the  transmission  of  cloud 
being  not  more  than  .20  (the  value  he  takes),  we  have  finally 

TS^A,  .99 
T*     A    .60' 
whence 

7\  =  .974  T, 

and  T  being  519.4°  Abs.  on  the  Fahrenheit, 

7\  =  505.7°,  that  is,  46.3°  F.  or  8°  C, 

a  result  substantially  the  same  as  we  have  deduced. 

Had  we  assumed  /J  to  be  .70  and  to  be  in  like  proportion  to  a  for 
Mars,  we  should  have  had 

T*=  1.140- 


and  7\4=  1.1011, 

Vi 

which  gives  not  far  from  what  we  had  before,  since  it  lowers  the  result- 
ing temperature  for  Mars  by  only  about  4°  F.  or  2°  C. 


256      MARS   AS   THE   ABODE   OF   LIFE 

13 

A  DUST  STORM  ON  MARS* 

On  May  25th  at  I5h  34m  G.  M.  T.,  Mr.  V.  M.  Slipher 
noticed  a  large  projection  about  halfway  down  the  ter- 
minator of  the  planet.  He  at  once  notified  me  and  we 
then  proceeded  to  observe  it  by  turns. 

What  first  impressed  me  was  its  size.  This,  both  in 
length  and  height,  was  excessive.  The  projection  con- 
sisted of  a  long  band  of  light,  a  little  north  of  the  centre 
of  the  arc  of  the  phase  ellipse,  lying  parallel  to  the  termi- 
nator but  parted  from  it  by  a  dark  line  half  the  band's  own 
width.  To  this  effect  I  made  a  sketch  of  it  at  1 5h  37m. 
The  next  thing  to  strike  the  eye  was  its  color.  This  was 
not  white  nor  whitish  but  ochre-orange,  closely  assimilated 
in  tint  to  the  subjacent  parts  of  the  disk,  the  region  to  the 
north  and  west  of  the  western  end  of  the  Deuteronilus. 
Such  distinctive  complexion  it  kept  throughout  the  time 
it  was  visible.  Coincidentally  Baltia,  then  close  on  the 
terminator  and  north  of  the  projection,  showed  white. 
The  seeing  was  5  on  a  scale  of  10 — sufficiently  good  to 
disclose  the  Phison  and  Euphrates  double  —  the  power 
310  and  the  aperture  that  of  the  24-inch. 

As  soon  as  possible  micrometric  measures  were  begun 
of  its  position  and  length,  the  position  angle  taken  being 
that  of  the  tangent  to  the  terminator  at  the  point  directly 
under  the  projection.  For  such  tangent,  together  with  the 
projection's  distance  from  the  disk,  furnishes  all  the  data 
necessary  to  determine  its  location.  Measures  of  this  angle 
were  repeated  at  intervals  during  the  time  of  visibility. 

At  I5h  41™  the  separation  of  the  projection  from  the 
terminator  seemed  to  have  sensibly  lessened  and  I  recorded 
it  in  another  sketch.  The  whole  projection  appeared  to 

*  Reprint  of  Lowell  Observatory  Bulletin,  No.  i,  June  9,  1903. 


NOTES  257 

have  moved  bodily  in.  At  51™,  however,  it  seemed  higher 
again  but  then  advanced  rapidly  toward  the  disk,  for  by  55™ 
only  the  tip  of  it  could  be  seen.  Thus  it  showed  for  some 
minutes,  being  last  seen  for  certain  at  i6h  8m  and  vanish- 
ing completely  after  i6h  iom. 

My  measures  and  notes  were  as  follows,  where  P.  A. 
denotes  the  position  angle  of  the  tangent  to  the  terminator 
as  above  described  :  — 

I5h  37m  Projection  on  terminator  —  found  about  five  min- 
utes before  by  Mr.  Slipher.  The  projection  is 
long  and  is  separated  from  the  terminator  by  a 
dark  line.  (Drawing.) 

41    P.  A.  2OO.°4  along  terminator. 

44  Projection  less  separated  from  terminator. 

(Drawing.) 
48    P.  A.  Projection  i99-°9. 

5 1  Length  projection  0.^92  ;  now  seems  higher  again. 

55    Just  about  gone  ;  only  the  tip  showing  apparently. 
No  striking  separation  now. 

i6h  iom  P.  A.  Projection  i99.°8;  only  suspected  by 
glimpses ;  surely  seen  last  at  i6h  8m. 

Impression  that  projection  had  moved  toward  north  as 
regards  Deuteronilus. 

During  the  course  of  the  observation  a  12-in.  diaphragm 
was  tried  once  but  in  this  case  without  gain.  At  the  same 
time  Mr.  Slipher's  measures  were  these :  — 

I5h  42m  (?)  P.  A.  Projection  2O3.0/. 

45  P.  A.  Projection  2O4.°O. 
Length  i."s8. 

52  P.  A.  Projection  2Oi.°o. 


258      MARS   AS   THE   ABODE   OF   LIFE 

Of  the  apparent  perpendicular  distance  of  the  top  of 
the  projection  from  the  terminator  our  respective  estimates 
were :  — 

By  Mr.  Slipher,  .067  of  the  radius  of  the  disk. 

By  me,  .075  of  the  radius  of  the  disk. 

These  estimates  were  got  from  measurements  of  our 
drawings  and  from  remembrance  of  the  size  of  the  pro- 
jection as  compared  with  the  size  of  the  disk. 

To  find  from  these  data  the  position  of  the  projection 
upon  the  planet  we  may  proceed  as  follows:  We  shall 
first  determine  the  height  of  the  highest  point  of  the  pro- 
jection above  the  planet's  surface. 

Taking  the  centre  of  the  disk  for  origin  and  the  minor 
axis  of  the  phase  ellipse  for  the  axis  of  x, 
let  d—  perpendicular  from  the  projection   upon   the   ter- 
minator. 
dl  —  distance   to   the   terminator   perpendicular   to   the 

phase  axis. 
r=  distance  from  the  centre  of  the  disk  to  the  foot  of 

the  perpendicular  d. 

t=  distance  of  the  projection  from  the  centre. 
-\/r  =  angle  between  r  and  t. 
%  =  exterior  angle  between  d  and  r. 
A  =  phase  latitude  of  the  tip,  or  its  latitude  in  the  aux- 
iliary circle  to  the  phase  ellipse. 
<£  =  angle  between  the  tangent  to  the  terminator  under 

the  projection  and  the  major  axis  of  the  ellipse. 
a  =  radius  of  the  disk,  in  seconds  of  arc. 
aQ  =  radius  of  the  disk  in  miles. 
h^  =  height  of  the  projection  in  the  plane  of  the  circle 

of  its  phase  latitude. 
h  =  its  true  height. 


NOTES  259 

£j  —  angle  in  the  plane  of  the  phase  latitude  circle  be- 
tween the  tip  of  the  projection  and  the  point  on 
the  terminator. 
|  =  same  in  the  plane  passing  through  the  origin,  the 

observer,  and  the  tip. 
6  =  angle  between  r  and  the  axis  of  x. 

x  and  y  the  coordinates  of  the  foot  of  d. 

xl  and  jj  those  of  the  foot  of  d-^. 

E  =  angle  of  the  phase. 

P  =  position  angle  of  the  polar  axis. 

Q  —  position  angle  of  the  phase  equator. 

B  =  latitude  of  the  centre  of  the  disk. 

X  =  longitude  of  the  centre  of  the  disk. 

By  a  property  of  the  ellipse  we  have 

tan  6  =  - 
also 


sin^  +  sec^cos2^ 
Then  in  the  triangle  made  by  r,  d,  and  t  we  have 


and  £  =  6  —  <f>, 

whence  we  can  findjj,  d^  and  then  A,  since 


Now 


sin  E  -  a  cos  A ' 

and  fi1=(secJ;l—i)aQ'CosA, 

then  since 

we  find  h. 


260      MARS   AS   THE   ABODE   OF   LIFE 

Since  the  height  of  the  projection  is  always  small  with 
regard  to  the  radius  of  the  disk,  we  may  take 


COS  9 


approx., 


and          tan  f  1  =  — approx., 

cos  9  sm  E  •  a  •  cos  A 

and  h  =  (sec  ^  —  i  )00  •  cos2  A  approx. 

If,  as  in  the  present  case,  the  projection  is  nearly  on  the 
phase  equator,  the  process  admits  of  still  greater  simplifi- 
cation. For  then  both  9  and  A  become  small  and 

tan  |  =  — : — -  approx., 
asmE 

and  h  =  (sec  |  —  i  )#0  approx. 

In  the  present  instance  the  height  distance,  from  my 

estimate,  is 

h=ij  miles. 

From  Mr.  Slipher's, 

h  =  14  miles. 

We  can  now  find  the  position.  Were  the  body  causing 
the  projection  upon  the  surface  of  the  sphere,  with  radius 
unity,  we  should  have  /  equal  to  the  sine  of  the  angle  from 
the  centre  of  the  disk  to  the  tip  of  the  projection.  Since 
in  reality  the  projection  is  raised  above  the  surface,  it  may 
be  considered  to  be  upon  the  surface  of  another  sphere 
concentric  with  the  first  and  of  radius  a  +  //.  The  point 
directly  under  it  will  not,  therefore,  be  where  the  tip  ap- 
pears. But  since  codirectional  lines  from  the  same  point, 
in  this  case  the  common  centre  of  the  two  spheres,  are 
altered  in  the  ratio  of  their  length,  however  projected,  we 
have  for  the  point  upon  the  planet's  surface  directly  under 
the  projection  a  distance  which  we  will  call/. 


NOTES  261 

The  angle  between  its  direction  and  that  to  the  planet's 
pole,  or  7,  is 


while  the  distance  in  angular  measure  to  that  pole  is  the 
colatitude  of  the  centre.  We  thus  have  two  sides  and  the 
included  angle  of  a  spherical  triangle  given  from  which  to 
find  the  colatitude  of  the  point  or  the  third  side  and  the 
lower  angle  or  the  longitude  of  the  point  from  the  centre 
of  the  disk. 

Thus  calculated  the  positions  of  the  projection  at  the 
several  moments  when  the  measures  were  taken  prove  to 
be  as  subjoined. 


G.  M.  TIME 

LATITUDE 

LONGITUDE 

May  26,  15  J  41™ 
48 
16   10 

i8°3i'N. 
19  44  N. 
21    24  N. 

39°  45' 
39  59 
40  33 

From  the  successive  positions  of  the  centre  of  the  pro- 
jection it  appears  that  that  centre  changed  its  place  during 
the  time  of  its  visibility.  It  was  three  degrees  farther 
north  and  three-quarters  of  a  degree  farther  west  at  the 
end  of  the  observations  than  it  had  been  at  their  begin- 
ning. Such  shift  could  be  due  to  either  of  two  causes. 
Bodily  transference  over  the  planet's  surface  would  account 
for  it ;  or  obliquity  of  tilt  of  the  projection's  medial  line  to 
the  terminator  would  produce  a  like  effect.  To  which  of 
the  two  possible  causes  the  result  was  to  be  attributed  was 
conclusively  shown  by  the  observations  of  the  next  day. 
It  is  worth  noticing  that  the  shift  was  recorded  in  the 
notes  as  impressing  itself  upon  the  eye  apart  from  the 
measures  and  confirmatory  of  them. 

At  I5h  5im  I  measured  the  length  of  the  projection 
along  the  terminator  and  found  it  to  be  o."g2.  If  we 


262      MARS   AS   THE   ABODE   OF   LIFE 

allow  o."i5  for  irradiation,  this  makes  it  o."//.  Now  the 
diameter  of  the  disk  at  the  time  was  io."^6  according  to 
Mr.  Crommelin's  ephemeris  which  takes  the  value  to  be 
9/'3O  at  distance  unity.  Mr.  Slipher's  measure  makes  it 
greater,  but  as  his  estimates  from  his  drawing  make  it 
less  we  may,  perhaps,  consider  the  above  as  a  fair  meas- 
ure. We  have,  then,  for  its  value  in  degrees  upon  the 
planet's  surface  and  in  miles  respectively :  — 

Length  of  projection  =  8.°2  =  300  miles. 

On  the  next  evening,  May  27th,  the  return  of  the  pro- 
jection's longitudes  off  the  terminator  was  duly  awaited. 
They  were  due  about  38™  later  than  on  the  preceding 
night,  but  in  order  that  if  the  projection  had  moved  to  the 
eastward  in  the  interval  it  might  also  be  caught,  observa- 
tions were  begun  some  time  beforehand.  My  notes  and 
measures  read  as  follows  :  — 

1 5h  40™  Cannot  certainly  see  anything  on  terminator, 
though  I  can  suspect  at  times  something  at 
its  centre  but  cannot  be  sure.  Seeing  3. 

44^  Suspect  something  just  below  centre  of  termi- 
nator. 

52    Distinctly  suspicious. 

58  Certainly  have  seen  a  small  projection.  P.  A. 
I95.°8.  Seeing  4. 

1 6     3    Thought  to  see  it  again. 

5    P.  A.  I96.°6,  had  previously  thought  it  higher 

(up  terminator).     Were  it  anything  like  that 

of  last  night,  it  must  certainly  have  been  seen. 

17    Can  see  nothing  on  terminator.    Seeing  a  good  5. 

27    Suspect   projection  again  but  cannot   be  sure. 

P.  A.    I96.°2.     Have   been   observing   about 

half  the  time. 


NOTES  263 

16    39  No  projection  visible.  Seeing  3. 

40  No  projection  visible.  Seeing  4. 

41  No  projection  visible.  Seeing  4. 
44  No  projection  visible. 

At  i6h  i5m  I  made  a  drawing  of  the  whole  planet  under 
seeing  as  good  as  on  the  night  before,  using  an  1 8-inch 
diaphragm  upon  the  24-inch  objective,  which  diaphragm 
was  also  employed  throughout  the  observations  recorded 
above. 

Mr.  Slipher,  who  observed  with  me  by  turns,  could  not 
detect  any  projection. 

From  these  observations  it  is  at  once  evident  that  the 
something  which  caused  the  projection  of  May  26th,  had 
ceased  to  exist  in  situ  and  in  size  on  May  2/th.  It  had 
changed  its  place  as  the  position  angles  show,  and 
had  greatly  diminished  in  extent  during  the  twenty-four 
hours  elapsed.  For  the  position  of  the  terminator  with 
regard  to  the  surface  was  substantially  the  same  as  on  the 
day  before.  Q-P  having  changed  in  the  interval  only 
+  o°.i3,  B  —  o.°02,  and  E  +  o.°2g.  The  chief  effect  of 
these  slight  alterations  of  phase  aspect  would  have  been 
to  delay  the  advent  of  the  projection  by  about  one  minute 
of  time. 

If  we  take  now  the  mean  of  the  two  measures  of  the 
position  angle  at  I5h  58™  and  i6h  5m,  we  find  for  the  posi- 
tion of  the  tip  of  the  projection  at  i6h  3In 


G.  M.  T. 

LATITUDE 

LONGITUDE 

May  27,  16"   3- 
and         i  6  27 

25°  29'  N. 
25   45   N. 

31°  43' 
36   5' 

Comparing  these  positions  with  those  of  May  26th,  we 
see  that  the  object  causing  the  projection  shifted  its  place 


264     MARS   AS   THE   ABODE   OF   LIFE 

over  the  surface  of  the  planet  from 

latitude  18°  31'  N.,  longitude  39°  45',  on  May  26th, 
to  latitude  25°  29'  N.,  longitude  31°  43',  on  May  27th, 

taking  the  time  of  greatest  apparition  on  both  occasions. 
It,  therefore,  moved  7°  in  latitude  to  8°  in  longitude  in  the 
twenty-four  hours,  or  390  miles,  at  the  rate  of  sixteen  miles 
an  hour.  From  this  we  infer :  First,  that  it  was  not  a 
mountain  or  mountains  illuminated  by  the  sun ;  and, 
second,  that  it  was  what  alone  fits  the  observations,  an 
enormous  cloud  travelling  northeast  and  dissipating  as  it 
went. 

Turning  now  from  the  observations  of  May  27th  to  those 
of  May  26th,  with  the  recognition  of  the  rate  of  shift  de- 
duced from  this  comparison  of  the  two  sets,  we  see  that 
the  change  of  place  recorded  by  the  first  night's  observa- 
tions is  to  be  ascribed  to  the  second  of  the  two  possible 
suppositions  mentioned  in  their  discussion,  or  to  the  form 
and  orientation  of  the  cloud.  Its  longer  axis  lay  E.  by  S. 
and  W.  by  N.  Its  axis  lay,  then,  roughly  speaking,  at 
right  angles  to  the  direction  of  its  motion.  This  is  further 
made  evident  by  the  measures  of  May  27th  in  which  the 
same  tilt  of  the  cloud's  axis  to  the  meridians  is  disclosed. 

We  shall  now  see  that  Mr.  Slipher's  observations  tell 
the  same  tale.  If  we  deduce  from  his  measures,  as  has 
been  done  by  Mr.  Lampland,  the  resulting  positions  of  the 
apparent  centre  of  the  projection  at  different  times  on 
May  26th,  we  find  as  follows :  — 


G.  M.  T. 

LATITUDE 

LONGITUDE 

i5h  42™ 

14°  52'  N. 

38°     2' 

45 

14   58  N. 

36  55 

52 

19     8  N. 

38    21 

NOTES  265 

Here  again  is  evident  a  tilt  of  the  axis  of  the  projection 
to  the  meridians,  such  that  the  following  end  lay  farther 
north  and  farther  west  than  the  preceding  end. 

It  is  of  interest  to  inquire  under  what  conditions,  diurnal 
and  seasonal,  the  cloud  came  into  being.  As  to  the  time 
of  day,  the  terminator  in  question  was  the  sunrise  one. 
The  cloud,  therefore,  was  first  seen  when  it  was  half  an 
hour  before  sunrise  upon  its  part  of  the  planet,  and  con- 
tinued to  be  visible  up  to  the  rising  of  the  sun.  The  place 
was  within  the  tropics,  in  the  desert  region  to  the  south 
of  the  Lacus  Niliacus.  With  regard  to  the  Martian  season 
of  the  year  it  was,  in  this  the  northern  hemisphere  of  the 
planet,  at  the  time,  according  to  the  data  of  Crommelin's 
excellent  ephemeris,  what  corresponds  to  the  first  of 
August  with  us  and  the  sun  was  overhead  in  latitude 
1 8°  7'  N.  The  cloud,  then,  when  first  seen  was  almost 
exactly  under  the  sun.  It  then  travelled  north,  dissipating 
as  it  went,  and  was  practically  dissolved  again  by  the  time 
it  had  reached  25°  N.  latitude. 

Finally,  its  color  leads  me  to  believe  it  not  a  cloud  of 
water-vapor,  but  a  cloud  of  dust.  Other  phenomena  of  the 
planet  bear  out  this  supposition. 

On  May  28th  no  trace  of  it  could  be  perceived  by  Mr. 
Slipher. 

14 
MARS  ON  THE  CAUSE  OF  AN  ICE-AGE 

In  a  paper  read  some  years  ago  before  the  American 
Philosophical  Society  *  the  writer  showed  that  Mars  was  at 
present  in  the  condition  to  offer  a  crucial  criterion  on  the 
correctness  of  Croll's  ingenious  theory  as  to  the  cause  of 
our  own  Glacial  Epochs,  and  that  the  evidence  presented  by 
the  planet  on  the  subject  did  not  wholly  support  the  theory. 

*  "  Mars  on  Glacial  Epochs."  Proceedings  Amer.  Phil.  Soc.,  Vol.  XXXIX, 
No.  164. 


266      MARS   AS   THE   ABODE   OF   LIFE 

Croll's  idea  was  that  increased  eccentricity  of  orbit  such  as 
was  true  of  the  Earth  in  the  past  brought  effects  in  its 
train,  —  change  of  ocean  currents,  increased  precipitation, 
and  so  forth,  — which  caused  a  glaciation  of  the  hemisphere 
possessing  the  long  cold  winters  and  the  short  hot  sum- 
mers. Study  of  Mars  showed  that  this  was  putting  the 
cart  before  the  horse;  that  increased  precipitation  from 
whatever  cause,  and  not  increased  eccentricity,  was  the 
trueflrimum  mobile  in  the  matter. 

The  evidence  offered  by  Mars  consisted  in  the  greatest 
and  least  size  of  its  two  polar  caps.  The  minima  were 
known ;  of  the  maxima  that  of  the  northern  cap  had  been 
determined  in  1897  at  the  Lowell  Observatory.  But  for 
the  southern  cap  only  seasonal  comparisons  with  the  north- 
ern at  corresponding  dates  enabled  its  maximum  to  be 
inferred. 

Since  then  the  actual  maxima  of  the  southern  cap 
have  been  observed  for  the  first  time,  and  their  direct  data 
more  than  support  the  deductions  of  the  previous  paper. 
We  may,  therefore,  conveniently  review  the  subject 
again. 

The  eccentricity  of  the  Earth's  orbit  at  present  is  .0168. 
In  the  past  it  has  been  greater,  fluctuating  up  and  down 
between  values  whose  extreme  upper  limit  is  .0747,  ac- 
cording to  Leverrier's  calculations.  Its  highest  amounts 
are  those  invoked  to  account  for  glacial  epochs.  At  the 
present  time  the  orbit  of  Mars  is  possessed  of  an  eccen- 
tricity about  five  and  a  half  times  our  own,  or  .0933.  It  is, 
therefore,  now  in  a  more  favorable  condition  for  eccen- 
tricity to  tell  than  our  Earth  ever  can  have  been. 

The  planet's  axial  tilt,  too,  upon  which  the  differential 
action  of  the  eccentricity  in  the  two  hemispheres  depends, 
is  about  that  of  the  Earth,  being,  according  to  the  latest 
measures,  those  at  Flagstaff  in  1907,  23°  13'  against  the 
Earth's  23°  27'. 


NOTES  267 

Furthermore,  these  two  quantities  in  the  two  orbits  are 
circumstanced  much  the  same,  the  line  of  apsides  and  that 
of  the  solstices  falling  in  both  not  far  apart.  With  Mars 
the  aphelion  of  the  orbit  lies  in  longitude  153°  19',  the 
summer  solstice  of  the  northern  hemisphere  in  longitude 
176°  48' ;  with  our  Earth  the  aphelion  is  in  longitude  280° 
21',  the  summer  solstice  of  the  northern  hemisphere  in 
longitude  270°.  Thus  both  planets  pass  the  points  of 
which  the  near  coincidence  is  vital  to  the  effective  working 
of  the  eccentricity,  in  fairly  close  succession.  With  Mars 
the  summer  solstices  follow  perihelion  and  aphelion ;  with 
the  Earth  they  precede  them.  This  has  the  effect  in  the 
northern  hemisphere  of  Mars  of  curtailing  the  end  of  sum- 
mer as  compared  with  its  beginning,  and  of  prolonging  it 
in  the  case  of  the  Earth ;  similarly  affecting  winter  in  the 
other  hemisphere.  On  the  other  hand,  in  the  southern 
hemisphere  of  Mars  summer  is  delayed  into  the  autumn, 
while  on  the  Earth  it  is  clipped. 

On  Mars,  then,  at  present  eccentricity  and  tilt  are  such 
as  to  counterpart  what  the  Earth  has  had  in  the  past,  only 
accentuated,  while  their  positioning  is  not  very  different  at 
the  moment  in  the  two. 

It  becomes  now  of  interest  to  note  what  the  result  of 
such  increased  eccentricity  is  on  Mars.  It  betrays  itself 
of  course  in  the  maxima  and  minima  of  the  two  caps. 
For  a  glacial  epoch  means  that  the  minimum  of  that  hemi- 
sphere's cap  is  a  maximum.  What  has  been  learned  on 
this  score,  then,  is  given  in  the  following  table :  — 


268      MARS   AS   THE   ABODE   OF   LIFE 


MARS 

NORTH  POLAR  CAP 
Minima 


1886  .   .   . 
1888  .   .   . 

1901    .     .     . 

1903  .   .   . 
1905  .   .   . 
1907  .    .    . 

Schiaparelli 
Schiaparelli 
Lowell 
Lowell 
Lowell 
Lowell 

78°-!  23° 

I28°-I72°  ? 

93°-  1  1  4° 
i24°-i5o° 
no°-i49° 
145° 

3-°5 
7-°o 
3-°o 
5-°o 
4.°6 
7-°7 

5-°i 

Maxima 

1897    .     .     . 
1907    .     .     . 

Lowell 
Lowell 

1  6  days  after  Aut.  Equi. 
8° 
273° 

77° 
90° 

84° 

SOUTH    POLAR   CAP 

Minima 

1862   .     .     . 

1879   .     .     . 
1894   .     .     . 

Lassell 

Schiaparelli 
Douglass  and 
Lowell 

70  days  after  solstice 
3U0 
3i8°-335° 

299° 

5-°5 
3-°8 
o.°o 

3-°i 

Maxima 

1903    ... 
1905    .     .     . 
1907   .     .    . 

Lowell 
Lowell 
Lowell 

135° 
117° 
142° 

104° 
104° 
103° 

104° 

NOTES  269 

Perusal  of  the  figures  proves  startling  to  the  theory  that 
eccentricity  of  orbit  is  responsible  for  glacial  epochs.  For 
they  show  that  at  its  minimum  the  southern  cap,  which  is 
the  cap  of  the  hemisphere  of  extremes  where  glaciation 
should  appear,  is  not  only  not  larger  than  the  northern  but 
is  actually  the  smaller  of  the  two.  And  this  in  face  of  a 
greater  precipitation  in  that  hemisphere  betrayed  by  the 
cap  itself.  For  at  its  maximum  it  surpasses,  as  the  table 
shows,  the  northern  cap  at  its  corresponding  season. 
Eccentricity,  therefore,  in  the  case  of  Mars,  far  from  caus- 
ing even  a  relative  glacial  epoch,  produces  exactly  the 
reverse. 

From  the  respective  maxima  and  minima  of  the  Martian 
caps  it  appears  that  the  short  hot  summer  of  the  hemi- 
sphere of  extremes  is  able  to  dispose  of  the  greater  deposit 
of  snow  of  that  hemisphere's  long  cold  winter.  Secondly, 
that  that  hemisphere's  precipitation  is  greater  than  that  of 
the  short  mild  winter  of  the  hemisphere  of  means ;  and 
thirdly,  that  its  short  summer  because  hot  is  more  effective 
in  melting  the  accumulated  ice  and  snow  than  the  long 
but  cooler  summer  of  its  antipodes.  For  it  reduces  a 
larger  maximum  to  start  with  to  a  smaller  minimum  in 
the  end. 

With  a  certain  amount  of  precipitation,  then,  to  wit  that 
existent  at  the  moment  on  Mars,  eccentricity  is  powerless 
to  cause  even  an  incipient  glacial  epoch.  Suppose,  now, 
the  precipitation  to  be  increased  generally  over  the  planet. 
The  melting  powers  of  the  summers  remain  unchanged, 
approximately,  except  that  with  more  deposit  more  fog  or 
cloud  would  be  raised  which  might  tend  to  handicap  the 
hotter.  With  precipitation  equally  increased  the  deposit 
would  be  more  in  the  long  cold  winter  in  the  climate  of 
extremes.  Its  maximum  would  be  raised  and  relatively 
to  a  greater  extent  than  in  the  other  hemisphere.  But 
since  the  quantity  melted  in  the  short  hot  summer  re- 


2;o       MARS   AS   THE   ABODE   OF   LIFE 

mained  as  before  or  even  diminished,  the  minimum  would 
be  correspondingly  raised  until  with  increase  of  precipita- 
tion the  minimum  of  the  climate  of  extremes  actually  sur- 
passed the  minimum  of  means  and  glaciation  set  in. 

Here,  then,  we  see  that  by  altering  the  amount  of  the 
precipitation,  from  any  cause  whatsoever,  an  anti-glacial 
condition  is  changed  into  a  glacial  one.  No  such  upsetting 
of  state  follows  a  change  in  the  eccentricity,  but  merely  a 
greater  or  less  accentuation  of  the  phenomena.  Eccen- 
tricity affects  the  degree,  precipitation  the  very  sign  of  the 
resulting  action.  Although,  therefore,  both  are  essential 
to  any  distinction  between  the  condition  of  the  two  hemi- 
spheres, it  is  the  amount  of  the  precipitation  that  really 
settles  the  matter.  And  the  cause  of  the  amount  need 
have  nothing  to  do  with  the  eccentricity.  Whatever  con- 
duces to  sufficient  increase  of  precipitation  will  cause  a 
glacial  epoch  irrespective  of  a  large  or  a  small  eccentricity. 
Furthermore,  as  no  planet  at  any  time  is  without  some 
eccentricity  of  orbit,  it  is  precipitation  that  determines  a 
glacial  epoch  or  the  reverse.  Mars,  then,  throws  this  light 
upon  the  problem :  it  teaches  us  that  glaciation  need  not 
result  from  eccentricity,  and  never  will  do  so  unaided  by 
a  factor  which  has  no  necessary  dependence  on  eccen- 
tricity at  all. 

15 
TIDAL  EFFECTS 

By  '  unhampered  age '  may  be  denoted  that  placid  course 
of  evolution  by  which  a  planet  goes  to  its  death  from  in- 
trinsic cause  alone.  For  a  planet,  like  a  man,  may  end  its 
life  for  other  reason  than  senility.  Like  him  it  is  subject 
to  many  vicissitudes  in  the  course  of  its  career.  One  cause 
of  world-extinction,  perhaps  the  commonest  of  all,  is  the 
tidal  action  due  the  Sun.  For  every  planet  that  rotates 


NOTES  271 

angularly  faster  or  slower  than  it  revolves  is  perforce  sub- 
jected to  enormous  partitive  strains.  Since  its  body  is  not 
absolutely  rigid  these  strains  become  tides,  superficial  or 
bodily,  which  act  as  brakes  to  bring  the  rotation  and  the 
revolution  to  coincide.  Eventually  such  synchronousness 
must  result ;  it  is  only  a  question  of  time.  When  it  befalls 
the  planet  that  body  ever  after  turns  in  perpetuity  the 
same  face  to  the  Sun.  This  fate  has0  already  befallen 
Mercury  and  Venus,  and  must  in  time  overtake  the  rest. 
One  side  of  the  planet  is  thenceforward  forever  baked ; 
the  other  forever  frozen.  Whatever  water  originally  ex- 
isted there  will  have  circulated,  caught  up  by  the  heated 
currents  of  the  sunward  side,  to  the  hemisphere  that  is 
turned  away,  there  to  be  deposited  as  ice.  This  alone 
would  terminate  all  possibility  of  life,  and  the  planet  roll 
a  mummified  mass  through  space. 

16 

ON  THE  VISIBILITY  OF  FINE  LINES 

The  minimum  visibile  of  the  normal  human  eye  is  com- 
monly taken  at  i'  of  arc.  In  other  words,  the  separating 
power  of  the  eye  by  which  two  objects  may  be  distin- 
guished as  distinct  has  this  for  its  minimum  distance  of 
effectibility.  The  limit  is  not,  however,  the  same  for  all 
eyes,  varying  from  individual  to  individual,  and  depends 
upon  what  is  known  to  oculists  as  acuteness  of  vision.  It 
is  something  quite  apart  from  near-sight  or  far-sight  and 
resides  apparently  in  the  fineness  of  the  retinal  rods,  some 
eyes  having  these  much  coarser  than  others.  Nor  is  it  the 
same  thing  as  sensitiveness  to  impression,  though  the  one 
ability  is  often  taken  erroneously  as  guarantee  for  the 
other.  Eyes,  however,  have  two  quite  distinct  capabilities, 
sensitiveness  or  the  power  of  distinguishing  faint  contrasts 


272      MARS    AS   THE   ABODE   OF   LIFE 

such  as  detecting  faint  stars,  and  acuteness  or  the  power 
of  resolution  of  parts  to  which  is  due  the  detection  of  plan- 
etary detail.  The  existence  of  the  one  faculty  does  not  in 
the  least  vouch  for  the  presence  of  the  other.  Indeed, 
experience  with  many  observers  has  shown  me  that  the 
two  are  rarely,  if  ever,  found  in  a  high  degree  together. 

Although  points  may  not  be  distinguished  as  a  rule  if 
they  lie  closer  together  than  i'  of  arc,  it  is  an  interesting' 
and,  at  first,  curious  fact  that  a  line,  having  a  breadth 
much  less  than  the  minimum  visibile  and  much  less  even 
than  what  would  enable  it  to  be  seen  were  it  a  point,  can 
be  distinctly  and  easily  perceived.  Michelson  has  shown 
theoretically  that  this  must  be  so,  and  has  further  experi- 
mented practically  to  the  same  conclusion.  Before  know- 
ing of  Michelson's  work  some  experiments  of  my  own  had 
shown  me  that  such  was  the  case,  as  indeed  every  one  un- 
consciously evidences  when  he  sees  a  spider-web.  My 
first  experiments  sufficed  to  show  me  a  line  whose  breadth 
was  less  than  2. "6  of  arc.  It  was  a  telegraph  wire,  seen 
against  the  sky,  whose  distance  away  was  then  measured. 
Recently  I  repeated  the  experiment  with  more  care  and 
with  the  results  which  follow. 

On  May  6  of  this  year  a  wire  was  stretched  by  Mr. 
Lampland  and  the  writer  from  the  top  of  the  dome  to  the 
top  of  the  anemometer  stand  near  it  in  such  a  manner  that 
it  could  be  seen  against  the  sky  down  a  vista  of  half  a 
mile  to  the  west.  The  wire  was  an  iron  wire  of  the  usual 
kind,  .0726  inch  in  diameter,  brownish  and  somewhat 
rusty.  In  color,  therefore,  it  was  not  very  dark.  We  be- 
gan to  observe  it  from  a  distance  of  500  feet,  at  which  it 
was  instantly  unmistakable,  up  to  2100  feet,  where  it  wholly 
ceased  to  be  visible.  The  distances  at  which  it  became 
less  and  less  perceptible,  the  character  of  that  perception, 
and  the  angular  width  of  the  wire  at  the  several  distances 
are  given  in  the  subjoined  table.  The  remarks  are  mine, 


NOTES 


273 


from  my  observations,  but  they  were  almost  exactly  con- 
curred in  by  Mr.  Lampland. 


VISIBILITY  OF  A  WIRE  .0726  INCH  IN  DIAMETER 


DISTANCE 

ANGULAR 
WIDTH 

REMARKS 

500  feet 

2."50 

Evident  at  first  glance. 

600  feet 

2.  "08 

Evident  at  first  glance. 

700  feet 

i."78 

Evident  at  first  glance. 

800  feet 

i."56 

Evident  at  first  glance. 

900  feet 

i.  "39 

Evident  at  first  glance. 

1000  feet 

i.  "25 

Easily  evident. 

i  ico  feet 

i.  "13 

Perfectly  visible. 

1200  feet 

i.  "03 

Distinctly  visible. 

1300  feet 

o."96 

Visible  but  not  easy. 

1400  feet 

o."Sg 

Visible  but  not  difficult. 

1500  feet 

o."83 

Visible  but  difficult. 

1600  feet 

o."78 

Glimpses  only. 

1700  feet 

o."73 

f  Well  glimpsed.    Imaginary  wires  glimpsed 
[     but  not  surely. 

1800  feet 

o"6o 

f  Well  glimpsed.     Imaginary  wires  glimpsed 

09 

{     but  not  surely. 

1900  feet 

o."66 

Glimpses  not  sure. 

2000  feet 

O."62 

It  and  imaginary  lines  of  equal  impression. 

2100  feet 

o.-sg 

Not  visible. 

It  is  interesting  to  note  the  fact  that  at  a  certain  stage 
of  difficulty  in  detection,  imaginary  wires  or  impressions 
of  wires  which  did  not  exist  were  reported  by  the  eyes  or 
the  optic  lobes  to  the  brain  and  that  such  could  be  distin- 
guished from  the  true,  not,  be  it  understood,  from  their 
position,  but  from  direct  subconsciousness  of  the  impres- 
sions they  made.  The  sight  of  a  wire  carried  with  it  at 
once  a  sense  either  of  certainty  or  of  doubt,  and  this  as 
the  table  shows  was  a  concomitant  of  the  strength  of  the 
impression.  Up  to  1800  feet  the  eye  or  brain  could  dis- 


274      MARS   AS   THE   ABODE   OF   LIFE 

tinguish  of  itself,  apart  from  position,  the  reality  or  ques- 
tionableness  of  the  impression.  At  1900  feet  and  still 
more  at  2000  feet  consciousness  was  unable  to  part  the 
false  from  the  true. 

To  apply  this  now  to  those  tenuous  lines  upon  the  sur- 
face of  Mars  known  as  the  "canals"  of  the  planet.  It 
may  be  well  to  say  in  premise  that,  when  seen  under  good 
conditions  of  air  and  observer,  they  are  not  bands  or 
washes  or  separating  shades,  but  perfectly  definite  lines 
which  range  all  the  way  from  such  as  might  be  made  by 
a  pen  and  india-ink  to  gossamers  like  spider-webs  seen  to 
the  naked  eye.  As  a  mean  case  of  distance  we  may  take 
the  planet  to  subtend  in  diameter  an  arc  of  14".  Suppose 
also  that  a  power  of  310  be  used,  which  is  also  a  mean 
power.  If  the  telescope  lost  no  light  and  the  definition 
through  it  were  as  good  as  to  the  naked  eye,  it  should  be 
possible  to  observe  a  line  on  the  planet  whose  width  was 

— '- — ^  x of  the  planet's  diameter. 

I4."o     310 

Now  the  planet's  diameter  in  miles  is  4220  ±.  In  miles 
then  the  width  would  be 

4220  x  ^  x_!_ 
I4."o     310 

or  |f  of  a  mile.     Say  f  of  a  mile. 

Were  the  planet  at  a  near  opposition  when  its  apparent 
diameter  is  over  24"  and  a  power  of  450  were  used,  we 
should  have  about  one-quarter  of  this  for  the  width  which 
might  be  seen,  or 

•ft  of  a  mile. 

As  the  telescope  does  lose  both  in  light  and  in  definition 
over  the  naked  eye,  it  would  not  be  possible  to  reach  this 
limit.  If,  however,  we  suppose  the  naked  eye  to  be  three 
times  as  effective,  it  would  seem  not  to  favor  the  telescope. 


NOTES  275 

At  this  estimate  J  mile  would  be  the  limiting  perceptible 
width. 

Why  a  line  can  be  seen  when  its  width  is  but  ^  of  the 
minimum  visibile  seems  to  be  due  to  summation  of  sensa- 
tions. What  would  be  far  too  minute  an  effect  upon  any 
one  retinal  rod  to  produce  an  impression  becomes  quite 
recognizable  in  consciousness  when  many  in  a  row  are  sim- 
ilarly excited.  Psychologically  it  is  of  interest  to  note  that 
there  are  stimuli  perceptible  so  faint  and  so  fleeting  as  to 
be  even  below  this  limit,  and  that,  unable  to  rise  into  direct 
consciousness,  leave  only  an  indefinite  subconsciousness 
of  their  presence  which  the  brain  is  unable  to  part  from 
its  own  internal  reverberations.  It  is  a  narrow  limbo,  this 
twilight  of  doubt,  since,  as  we  see  in  the  present  instance, 
below  o."59  the  object  produced  no  effect,  and  above  o."6g 
the  brain  was  cognizant  of  objectivity  as  such. 


NOTES  ON  VISUAL  EXPERIMENT 

The  following  visual  experiment  was  performed  at  the 
request  of  Director  Lowell,  and  the  notes  may  be  con- 
sidered as  supplementary  to  those  of  the  experiment  on 
the  visibility  of  a  wire*  —  the  experiments  being  identical, 
except  that  in  the  last  instance  a  disk,  having  a  fine  line 
of  same  width  as  wire  ruled  across  its  face,  was  observed 
along  with  the  wire. 

As  a  check  against  any  influence  that  a  knowledge  of 
the  positions  of  the  wire  and  line  might  introduce,  the  ob- 
server V.  M.  S.  had  nothing  to  do  with  the  preparation  and 
arrangement  of  the  experiment,  and  made  his  observations 
going  toward  the  disk  and  wire,  the  observations  being 
begun  at  the  extreme  limit  of  visibility  for  the  line  and 
wire. 

*  Lowell  Observatory,  Bulletin  No.  2. 


276      MARS   AS   THE   ABODE   OF   LIFE 

For  each  series  the  results  are  practically  the  same  for 
the  two  observers  —  the  one  having  no  knowledge  as  to 
the  positions  of  the  objects  and  making  his  observations 
going  towards  them,  the  other  beginning  observations  near 
the  objects  and  going  away  from  them. 

V.  M.  SLIPHER. 
C.  O.  LAMPLAND. 
December,  1903. 

Wooden  disk  eight  feet  in  diameter,  covered  with  white 
paper,  with  fine  blue  line,  .07  inch  wide,  ruled  across  its 
face.  Line  on  disk  makes  about  same  angle  with  hori- 
zontal as  wire  stretched  above  it.  Disk  suspended  from 
cable,  stretched  from  top  of  dome  to  a  pine  to  the  south- 
west. Plane  of  disk  nearly  in  the  meridian.  Wire  same 
width  (.07  in.)  and  color  as  that  used  in  the  original  ex- 
periment. (Lowell  Observatory  Bulletin  No.  2.) 

FIRST  SERIES 

Station 

100  ft.   Wire  and  lines  on  disk  very  distinct.  —  c.  O.  L. 
Angular  width  :  disk,  4°  35' ;  lines,  12." 48. 

200  ft.  Line  stronger  than  wire.  —  v.  M.  s. 

About  the  same  as  the  100  ft.  station.  — c.  o.  L. 

Angular  width  :  disk,  2°  17/5  ;  lines,  6."24- 
300  ft.  Line  stronger  than  wire.  —  v.  M.  s. 

Both  wire  and  line  on  disk  strong  and  well  seen.     Perhaps 
line  the  stronger.  —  c.  O.  L. 

Angular  width  :  disk,  i°  31/7 ;  lines,  4/'i 6. 

400  ft.  Line   the  stronger.      Probably  due  to   background   offering 
greater  contrast.  —  v.  M.  s. 

About  as  well  seen  and  as  evident  as  at  300  ft.  station.  — c.  O.  L. 

Angular  width :  disk,  i°  8/8  ;  lines,  3. "12. 
500  ft.  Wire  and  line  equally  sharp  and  evident.  —  v.  M.  s. 

Wire  and  line  evident  and  distinct  at  first  glance.  —  c.  o.  L. 

Angular  width :  disk,  55' ;  lines,  2. "50. 

600  ft.   Disk  in  shadow,  yet  line  well  seen,  as  is  also  wire.     Line  more 
permanently  visible,  perhaps.  —  v.  M.  s. 


NOTES  277 

Line  on  disk  distinct  and  evident,  but  becoming  more  difficult. 
Illumination  very  bright  and  glaring.     Wire  distinct  and 
evident  first  glance.  —  c.  o.  L. 
Angular  width  :  disk,  45/8 ;  lines,  2. "08. 
700  ft.   Inaccessible. — v.  M.  s. 

Poor  station  for  observation.  — c.  o.  L. 
Angular  width  :  disk,  39/3  ;  lines,  I. "78. 
800  ft.   Inaccessible.  —  v.  M.  s. 

Wire  comes  out  very  distinctly  —  stronger  at  times.  Line  on 
disk  becoming  more  difficult  —  somewhat  difficult  at  times 
from  this  station,  but  perfectly  evident  with  good  illumina- 
tion.—  c.  o.  L. 

Angular  width  :  disk,  34/4;  lines,  I. "56. 
900  ft.   Can  see  wire.     Disk  in  shadow  of  tree.  — v.  M.  s. 

Angular  width  :  disk,  30/6;  lines,  i."39- 

1000  ft.  Wire  more  difficult  but  perfectly  evident.  Line  on  disk  also 
becoming  difficult,  but  glimpse  it  definitely  with  good  illumi- 
nation. —  c.  o.  L. 

Angular  width  :  disk,  27/5  ;  lines,  i."25. 
noo  ft.   Can  see  wire  and  line.     Shadow  is  on  disk.  —  v.  M.  s. 

Both  wire  and  line  on  disk  perfectly  and  distinctly  seen.  — 

c.  o.  L. 

Angular  width  :  disk,  25' ;  lines,  I."i4. 
1 200  ft.   Certainly  glimpse  line;  poor  glimpses  of  wire.  — v.  M.  s. 

Wire  rather  difficult  and  at  times  not  seen,  but  glimpsed  per- 
fectly at  intervals.     Line  on  disk  glimpsed  distinctly  at 
times  when  angle  of  illumination  changes. — c.  O.  L. 
Angular  width  :  disk,  22/9;  lines,  I."o4. 
1300  ft.   Certainly  glimpse  line  and  wire.  —  v.  M.  s. 

Wire  difficult  now,  but  glimpsed  at  times.    Line  on  disk  fairly 
well  glimpsed  as  wind  swings  disk,  but  becoming  difficult  — 
somewhat  faint.  —  c.  o.  L. 
Angular  width  :  disk,  21/2;  lines,  o."96. 
1400  ft.  Do  not  glimpse  either  wire  or  line.     Hasty  observations. — 

v.  M.  s. 
Line  on  disk  glimpsed  at  times  as  disk  swings,  but  faint,  diffuse, 

and  difficult.    Wire  glimpsed  but  difficult.  —  c.  o.  L. 
Angular  width  :  disk,  19/6  ;  lines,  o."Bg. 

1450  ft.    Certainly  glimpsed  wire.     Cannot  certainly  glimpse  line.     I 
get  glimpses  of  a  fictitious  as  well  as  what  I  take  to  be  a 
real  line.     It  is  (if  glimpsed)  illy  defined.  — v.  M.  s. 
Angular  width  :  disk,  19';  lines,  o. "86. 


278     MARS   AS   THE   ABODE   OF   LIFE 

1500  ft.   Wire  at  this  station  extremely  difficult.     Not  certain  that  I 
glimpse  it.     Line  on  disk  seen  at  times,  but  now  feint  and 
diffuse.     Shadow  of  tree  on  part  of  disk.  —  c.  o.  L. 
Angular  width  :  disk,  18/3;  lines,  o. "83. 

1600  ft.  Wire   not  certainly  glimpsed :    imaginary  wires  seem  about 
equally  strong.     Shadow  of  tree  on  disk,  obscuring  line.  — 
c.  o.  L. 
Angular  width :  disk,  17/2;  lines,  o/'/S. 

SECOND    SERIES 

Same  disk,  and  wire  for  comparison,  as  used  in  the  first 
series  of  these  observations. 
Station. 

ico  ft.   Wire  and  line  on  disk  very  distinct  and  clear  cut.  — c.  o.  L. 
200  ft.    300  ft.  station  remarks  hold. — v.  M.  s.     (Observations  made 

going  towards  wire  and  disk.) 
About  the  same  as  at  100  ft.  station.     Line  the  stronger.  — 

c.  o.  L. 
300  ft.   400  ft.  station  remarks  hold.  — v.  M.  s. 

Well  defined  at  first  glance  —  both  wire  and  line  on  disk,  line 

perhaps  the  stronger.  —  c.  o.  L. 

400  ft.    Line  easier  than  wire  and  more   definite.     (Due  to   back- 
grounds ?)  — v.  M.  s. 
Distinct  and  well   seen  at  first  glance.     (Line  appears  the 

stronger).  —  c.  o.  L. 

500  ft.   Line  more  definite  than  wire.     (Some  telephone  wires  pass 
before  the  disk ;   these  are  easier  and  more  definite  than 
wire.) — v.  M.  s. 
Distinct  and  well  seen  at  first  glance.     No  appreciable  difference 

from  400  ft.  station.  — c.  o.  L. 
600  ft.   Line  easier  than  wire,  except  where  the  latter  crosses  cables. 

(Cables  from  which  disk  is  suspended.)  —  v.  M.  s. 
Wire  and  line  on  disk  seen  with  perfect  ease  and  distinctly, 
but  fainter  than  at  500  ft.  station  —  seen  at  first  glance.  — 

C.  O.  L. 

700  ft.    Line  easier  than  wire.  —  v.  M.  s. 

800  ft.    Disk  inaccessible.     Wire  seen.  —  v.  M.  s. 

Poor  station.     Trees  interfere  with  observations.  —  c.  o.  L. 
900  ft.   Wire  and  line  only  fairly  seen.  —  v.  M.  s. 

Wire  quite  well  seen  but  somewhat  faint  and  diffuse.     Line  on 
disk  glimpsed  at  times  but  difficult.     Disk  very  bright  — 


NOTES  279 


Illumination  not  the  best  for  seeing  line.  Later :  Line  seen 
quite  well  when  the  disk  was  swung  by  the  wind.  Faint.  — 
c.  o.  L. 

1000  ft.   Inaccessible.  —  v.  M.  s. 

Wire  glimpsed  at  instants.     Disk  obscured  by  trees.  —  c.  O.  L. 

uoo  ft.   Line  well  glimpsed  :  wire  doubtfully.  —  v.  M.  s. 

Wire  glimpsed,  but  faint  and  diffuse  and  not  visible  all  the 
time.  Line  on  disk  distinctly  seen  when  disk  swings  around 
for  favorable  illumination.  — c.  o.  L. 

1 200  ft.   Glimpse  wire  rather  doubtful.     Line  and  wire  glimpsed  some- 
what more  certainly  than  at  1300  ft.  station. — v.  M.  s. 
Wire  very  difficult  — glimpsed  but  faint  and  diffuse.     Line  on 
disk  glimpsed  but  faint.  —  c.  o.  L. 

1300  ft.  See  some  markings  on  disk  as  before,  i.e.,  in  second  and  fourth 
quadrant.  Perhaps  glimpse  wire.  Line  more  definitely 
glimpsed.  — v.  M.  s. 

Wire  very  difficult  —  glimpsed  at  intervals  —  diffuse  and  some- 
what uncertain.  Line  on  disk  also  very  difficult  most  of  the 
time ;  very  faint  and  diffuse.  As  disk  swings  from  wind  it 
is  distinctly  glimpsed  at  times.  —  c.  o.  L. 

1400  ft.  Glimpse  line  and  have  occasional  glimpses  of  fictitious  markings 
(on  disk) .  I  once  imagined  I  glimpsed  wire.  There  is  a 
dark  spot  in  second  quadrant,  and  glimpse  line  from  o°  to 
290°.  —  v.  M.  s. 

Cannot  certainly  say  that  I  glimpse  wire  —  now  of  about  same 
strength  as  imaginary  wires.  Line  on  disk  fairly  well 
glimpsed  at  times,  as  disk  swings,  but  faint  and  diffuse.  — 
c.  o.  L. 

1500  ft.  Cannot  see  wire.  Suspect  it  and  line  on  disk  at  times,  but 
uncertain.  —  c.  O.  L. 

17 

CANALS  OF  MARS 

At  the  opposition  of  1907,  264  canals  were  seen  and 
drawn  by  the  writer ;  a  large  number  also  by  Mr.  C.  O. 
Lampland ;  and  many,  including  some  new  ones,  by  Mr. 
E.  C.  Slipher  in  South  America,  not  yet  catalogued  and 
mapped. 


28o      MARS   AS   THE   ABODE   OF   LIFE 

Of  the  264  canals  mapped,  85  were  new.  Owing  to  the 
tilt  of  the  axis  and  to  the  Martian  season  of  the  year,  these 
were  mostly  not  only  in  the  southern  hemisphere  but  in  the 
more  southern  part  of  it.  The  position  of  the  new  canals 
was  as  follows :  — 

1)  32  in  the  light  regions. 

2)  34  in  the  dark  regions  or  in  those  of  intermediate  tints. 

3)  12  in  or  through  the  southern  'islands.' 

4)  _7  at  the  edges  of  dark  regions. 

85  in  all. 

Added  to  those  already  recorded  these  make  :  — 

336  +  32  =  368  in  the  light  regions.  (i 

101  +  53  =  154  in  the  dark  ones.  (2,  3,  4 

522  in  all. 

Of  the  canals  seen  28  were  double  or  about  ^  of  the  whole 
number  showing.  Those  not  hitherto  so  seen  were  the 

Cyclops  II 

Cambyses  (?) 

Ambrosia 

Glaucus 

Bias 
making  56  doubles  in  all. 

18 

POSITION  OF  THE  Axis  OF  MARS 

WHICH   DETERMINES   THE   SEASONS   ON   THE  PLANET 

The  position  of  the  pole  of  Mars,  determined  by  Lowell 
in  1905  from  a  synthesis  of  his  own  observations  on  the 
polar  caps  and  of  previous  ones  of  the  same,  was :  — 

R.A.  3i;.°5         Dec.  54°$ 


NOTES  281 

This  gave  for  the  tilt  of  the  Martian  equator  to  the  Martian 
ecliptic 

23°  59'. 

This  position  of  the  axis  of  Mars  was  adopted  by  the  British 
Nautical  Almanac.  The  same  is  to  be  incorporated  in  the 
American  Ephemeris. 

In  1907  two  very  full  series  of  observations  on  the  south 
cap  were  obtained  at  Flagstaff  which  confirmed  the  several 
previous  series  taken  there,  suggesting  that  still  greater 
weight  should  be  given  them  in  the  synthesis  than  had 
previously  been  assigned.  The  resulting  inclination  of  the 
Martian  equator  upon  the  Martian  ecliptic  is 

23°  13'. 


INDEX 


Aeria,  209. 
Air,  12. 
thinning  of,  no  bar  to  a  species,  96, 

97- 

on  mountain  tops,  98. 

of  Mars,  139,  186. 

density   at   Martian   surface,   Notes 

239-240. 
Albedo, 

of  Mars,  78,  84. 

of  Venus,  78. 

of  each  planet,  84,  Notes  249. 

of  Earth,  Notes  247. 
Amphibia,  53. 
Animal  life, 

on  peaks,  103. 

dependent  on  temperature,  103. 
Antarctic  zones,  183. 
Aqueducts  of  Carthage,  128. 
Arabia,  125. 

Arctic  zones  of  Mars,  183. 
Areolas  of  Mars,  151. 
Arequipa,  153. 
Arethusa  Lucus,  196. 
Artificiality, 

of  Martian  markings,  195. 

of  canals,  211. 
Ascraeus  Lucus,  157. 
Asia,  deserts  of,  125. 
Asteroids, 

later  found  less  evident  than  earlier, 

ISI- 
Astronomy, 

(gravitational,  i. 
physical,  i. 
Atmosphere, 
of  Mars,  77,  Notes  238. 
shown  by  cloud,  78. 
evidence  from  albedo,  78. 
proved  by  limblight,  79. 
by  changes  in  surface  features,  80. 
polar  caps  first  to  betray,  80. 
circulation  of,  130. 
~  amount  of,  Notes  238. 


Axial  tilt, 

of  Earth,  71,  Notes  266. 

of  Mars,  77,  Notes  266. 
Axis  of  Mars,  Notes  280. 

Beer,  81. 

Blondet,  M.,  48,  Notes  232. 

Blue  band, 
surrounding  polar  caps  of  Mars,  81-82. 

Blue-green  areas  of  Mars,  104-106,  133, 
164. 

Bolometer, 

use    in    surface    temperature    deter- 
mination, 85. 

Boltzmann,  86. 

Ceenozoic  time,  45. 
Cambrian  era,  45. 
Campbell,  138. 
Canals, 

discovery  of,  146. 

geometric  look"  of,  147. 

as  straight  lines,  148: 

breadth  of,  149,  160. 

length  of,  149. 

in  dark  regions,  152-153. 

rendezvous  at  special  points,  152. 

photographed,  154. 

superposed  over  main  features,  155. 

double,  i59-i67,/l9tf^ 

direction  of,  164-165.' 

subject  to  change,  167. 

research,  new  method  of,  168. 

career  of,  171. 

cartouches  of,    172-175,  Notes  249. 

quickening  according  to  latitude,  1 75. 

quickening  starts  at  polar  caps,  1 76. 

vegetation  explains  behavior,  177. 

advent  of  water  down  the,  181. 

not  cracks,  191. 

not  rivers, 

nerve  and-CIJ5Iy '  210. 


284 


INDEX 


Carbon  dioxide, 

amount   in  atmosphere  in  paleozoic 
times,  51. 

a  bar  to  the  passage  of  heat,  51. 

on  Mars,  104,  107. 

influence  on  climate,  Notes  236-237. 

effect  of,  on  planets,  Notes  237. 
Carboniferous  periods,  45,  53. 

heat  of,  47-48. 

little  light  in,  47-48. 
Carets  of  Mars,  212. 
Carthage, 

aqueducts  of,  128. 

desert  character  now,  129. 
Cartouches,  of  canals,  172-175,  Notes 

249. 

Casius,  wedge  of,  133. 
Ceraunius,  1 73,  1 76. 
Chagos  Archipelago,  121. 
Chalcedony, 

tree  trunks  changed  to,  127. 
Challenger  expedition,  42,  59,  62-63. 
Chart, 

bathymetric,  33. 
Chemical  affinity, 

relation  to  plants,  36. 

relation  to  stones,  37. 

life  a  manifestation  of,  37. 
Clouds, 

on  Mars,  22,  52,  77-78,  85-86. 

on  Earth,  85. 
Conifers,  70. 
Continents  of  Mars,  146. 
Coral  reefs, 

found  only  in  warm  seas,  46. 

in  past  ages,  71. 
Cowper,  17. 

Cretaceous  period,  64,  71. 
Croll,  112-113,  Notes  265. 
Crommelin,  Notes  262. 
Crova,  Notes  244. 
Crusts  of  planet, 

formed  over  molten  mass,   13-14. 

crinkling  of,  result  of  cooling,  14-15. 

crinkling  of,  where  most  pronounced, 
15- 

knowledge  of,   derived  from   Earth, 

Moon,  Mars,  14,  16. 
Crustacea,  60. 
Cryptogams,  47,  70. 
Cycads,  70-71. 

Dana,   Professor,   119. 
Darwin,  Sir  George,  26. 


Day, 

length  of  Martian,  77. 
Dead  stage, 

of  planetary  career,  12. 

Moon  and  larger  satellites  in,  12. 
Density, 

Laplacian  law  of,  24. 

meteoric,  28. 

of  the  Earth,  14. 

of  the  Earth's  surface  rocks,  14. 
Desert-belts, 

girdling  Earth,  124,  129. 

on  Mars,  131. 
Deserts, 

on  Earth,  124. 

on  Mars,  134. 
Devonian  era, 

plants  found  in,  46. 
Djihoun,  161,  203. 
Douglass,  A.  E.,  153,  200. 
Dust  storms  on   Mars,  22,  89,  Notes 
256-265. 

Earth,  planetary  career  of,  13. 
Eccentricity, 

of  Earth's  orbit,   Notes  266. 

of  Mars'  orbit,  Notes  266. 
Elements, 

existing  if  water  be  present,  39-40. 
Elysium,   160. 
Eocene  period,  72. 
Eumenides-Orcus,  149,  151,  156. 
Euphrates,  213,  Notes  256. 
Europe, 

gain  of  land  in,  120. 
Evolution, 

planetary,  i,  3-34- 

of  life,  35-69. 

Earth  not  Sun  the  motive  force  of, 
52,  72- 

effect  of  environment  upon,  54. 

general  principle  of,  69. 

steps  of,  108-110. 

of  Earth  and  Mars,  73,  186. 

Fal,  57- 
Fauna,  45,  58. 
Fossils, 

evidencing  planetologic  eras,  44-46, 
70-71. 

Galitzine,  86. 
Ganges,  205. 
Gardiner,  Stanley,  121. 


INDEX 


Generation,  spontaneous,  37,  67. 
Geology,  a  part  of  planetology,  13. 
Glaciation, 

Mars  not  suffering  from  wholesale,  89. 
Gravity,  on  Mars,   210,  Notes  232. 
Gymnosperms,  70. 

Habitability  of  Mars,  96-97. 
Habitat,  of  animals,  129. 
Habitation, 

of  Mars,  215. 

destined  to  pass  away,  216. 
Haeckel,  39. 
Heat, 

substances  vary  with,  8. 

radiation  of,  in  planetary  evolution, 
9-10,  25. 

of  paleozoic  times   excessive,  48-51. 

acquired  by  the  Moon,  Notes  230. 

of  Martian  surface,  Notes  231. 

received  by  Earth  and  Mars,  Notes 
250. 

retained  by  Earth  and  Mars,  Notes 

251-255- 
Heat  of  condensation, 

dependent  on  mass,   7-8,  23. 

for  homogeneous  body,  7-8,  24. 

for  heterogeneous  body,  8,  24. 

evaluated  for  Earth  and  Moon  sup- 
posing origin  the  same,   24-25. 

compared  for  Earth  and  Mars,  27. 

developed  by  planetary  contraction, 

Notes  225-229. 
Hibernation,  90,  96. 
Himalaya, 

snow  line  and  timber  line  on,  99. 
Huygens,  i,  138. 

Icarii  Luci,   212. 
Ice-age, 

Mars  on  the  cause  of,  Notes  265. 
Illumination,  slant,  17. 

heights  of  mountains  measured  by,  18. 
Indo-Pacific,  coral-reef  region,  121. 
Isoflors  in  Arizona,  100. 

Janssen,  138. 
Jurassic  period,  71. 

Lampland,  C.  O.,  154-155,  Notes  264, 

272,  276-279. 

Landscape,  the  result  of  cooling,  14. 
Langley,  85,  88,  Notes  241. 
Laplace,  i,  24. 


Lapparent,  de,  48,  68,  Notes  233. 
Life, 

origin  of,  35. 

an    inevitable    phase    of    planetary 
evolution,  37,  66. 

a  manifestation  of  chemical  affinity, 
37,  38. 

water  essential  to,  39. 

outgrows  the  sea,  53,  55,  68. 

adaptability  of,  56,  96,  97. 

deep-sea,  57-64. 

cosmic  character  cf,  64. 

did  not  reach  Earth  from  without,  66. 

the  outcome  of  planetary  cooling,  66. 

mode  of  manifestation,  107. 

types  of,  142. 

chemical  constituents  of,  1 79. 
Limblight, 

proves   existence  of  atmosphere  on 

Mars,  79. 

Little  Colorado,  127. 
London,  size  of,  214. 
Lower  Silurian  era, 

wings  of  insects  found  in,  46. 
Lucus  Phoenicis,  161. 

Madler,  81. 

Man,  first  appearance  of,  68. 

Mare  Acidalium,  133. 

Mare  I  car  turn,  158. 

Mass,  15,  16,  31,  39. 

the  fundamental  factor  of  planetary 
evolution,  9. 

comparative,  of  Earth,  Moon,  Mars, 

16. 

Maxwell,  Clerk,  139. 
May-flies,  of  Carboniferous  era,  47. 
Mercury,  markings  of,  192-193. 

rotary  retardation  of,  207. 
Merriam,  Dr.,  90,  95,  99. 
Mesozoic  time,  45,  71. 
Metamorphic  rocks,  12. 

age  of,  12. 

akin  to  furnace  slag,  13,  14. 
Meteoric  swarms, 

gravitational  heat  of,  7,  8,  67. 
Meteorites,  4,  34. 

constitution  of,  4,  6. 

size  of,  4. 

velocity  of,  4,  5,  Notes  220-225. 

fused  by  friction  with  atmosphere,  4. 

worship  of,  4,  5. 

relation  to  solar  system,  4-6. 

oldest  bits  of  matter,  5. 


286 


INDEX 


Meteorites  —  Continued. 

occluded  gases  in,  6. 

density  of,  28. 

members  of  solar  system,  Notes  225. 
Michelson,  Notes  272. 
Mind, 

beings  revealed  by,  no. 

evidence  of,  143-144. 

effect  on  planetary  markings,  215. 
Miocene  period,  68,  72. 

edible  plants  and  plant  eaters  in,  68. 
Molecule,  organic,  35-36. 

six  elements  of  the,  37-38. 

relation  of  atoms  to,  producing  vital 

actions,  37. 
Molten  stage,  12. 

Neptune,  Uranus,  Saturn,  and  Jupiter 

in,  12. 
Moment  of  momentum, 

of  solar  system,  3,  Notes  219. 

of  Alpha  Centauri,  Notes  220. 
Mountains, 

proportional  to  mass  of  planet,  15. 

none  on  Mars,  16,  19,  20-22. 

heights  measured  by  slant  illumina- 
tion, 1 8. 

on  Moon,  19,  23,  27,  Notes  229-230. 
Mt.  Whitney, 

bolometer    investigations    at,    Notes 

242. 
Muller,  84. 

Newton,  i. 

Nilokeras,  161. 

Nitrogen,  on  Mars,  104,  107. 

connection  with  life,   179. 
North  America,  gain  of  land  in,  119. 
Novae, 

an  analogue  of  prehistoric  cataclysms, 
6. 

Oases, 

first  seen,  157. 

form,  demonstration  of  function,  157, 

195- 

shape  of,  197. 

behavior  of,  197. 

probable  meaning  of,    213-214. 
Oblateness  of  Mars,   199. 
Obliquity  of  Martian  ecliptic,  Notes  281 . 
Oceans,  12. 

origin  of,  28. 

distribution  of,  on  Earth  and  Mars, 
28-30. 


Oceans,     relative     size     on     different 

planets,  30-32. 
Moon  more  profusely  endowed  with, 

32- 

basins  of,  unchanged,  32-34. 

basins  of,  on  Mars,   132. 

character  of  bottoms  of,  33,  34. 

cooling  of,  occasioned  development  of 
higher  forms  of  life,  43. 

of  Earth,  disappearing,  118. 

on  Earth,  141. 

absent  on  Mars,  112,  187. 
Oligocene  period,  72. 
Orbit, 

eccentricity  of  Earth's,  Notes  266. 

eccentricity  of  Mars',  Notes  266. 
Organisms, 

evolution  of,   205. 
Origin  of  Moon,  25. 

Darwinian  theory  of,  26. 

explained  by  heat  investigation,  25-27. 
Oxygen, 

the  chief  factor  in  all  organisms,  38. 

one-half  the  substance  of  the  Earth's 
surface,  38. 

on  Mars,  104,  107,  137. 

connection  with  life,   179. 

Paleozoic  time,  45. 
light  less  and  heat  more  than  now, 

48,  51. 
light  and  heat  of,  not  explained  by 

Sun,  49-50. 
Earth  itself  responsible  for  heat  of, 

So,  52- 

Palestine,  129. 
Permean  period,   54. 
Petrified  forests  of  Arizona,   125,   126. 
Phison,  158,  213,  Notes  256. 
Phcenix  Lake,  149. 
Pickering,  W.  H.,  153,  157. 
Pigments,  put  on  by  the  Sun,  72. 
Planet, 

life  history  of,  dependent  on  size,  u. 
internal   heat   of,    its   initial   motive 

power,  13. 
cooling  the  mode  by  which  its  energy 

worked,  9-10,  13,  28. 
Planetology, 

the  connecting  link  between  nebular 
hypotheses  and  the  Darwinian 
theory,  2. 

six  eras  of,   11-12. 
geologic  part  of,  13-14. 


INDEX 


287 


Plant  life. 

Carboniferous,  46-48,  51. 

light  a  necessity  to,  58. 

not  existent  in  deep  seas,  63. 

entrance  of  plant  eaters  with,  68. 
Plateau, 

temperature    of,  as    compared    with 
peaks,  99. 

Pliocene  period,  72. 
Polar  caps, 

of  Mars,  So,  204. 

constitution  of,  81-82. 

not  solid  carbonic  acid,   81—82. 

of  Earth,  ourselves  dwellers  in,  90. 

diminish,  114. 

snows  of,  1 80. 

canals  from,  197. 

water  of,  204. 

Notes,  268. 
Portus  Sigaeus,   158. 
Precipitation, 

of  snow,  Notes  269-280. 
Pressure, 

substances  vary  with,  8. 
Projections, 

on  Martian  terminator,  20. 

not  indicative  of  mountains,  21. 

due  to  dust  clouds,  22. 
Proponiis,  133. 
Protonilus,  158. 
Protoplasm, 

first  possible  with  formation  of  water, 
35- 

nine-tenths  water,  41. 

first  existed  in  water  at  a  high  tem- 
perature, 42. 

formed,    the    moment    cooling    per- 
mitted, 67. 
Pseboas  Lucus,  158. 

Radiant  energy, 

reflection   of,   from  atmosphere  and 

surface  of  planet,  83-84. 
Rainfall, 

on  Earth,  130. 
Reptiles,  advent  of,  54. 
Rills,  of  the  Moon,  191. 
Rotation  of  Mars,   75-76. 
Roughness, 

relative,  of  Earth,  Moon,  Mars,  16. 

exception  to  theoretic  order,  23. 

Sabaeus  Sinus,  212. 
Sahara,  the,  125. 


San  Francisco  Peaks,  90,  127. 

zones  of  vegetation  on,  93-94. 

animal  life  on,  95-97. 

life  on,  103. 
Sarasin,  57. 
Schiaparelli,   104,   146,   147,   151,   152, 

170. 
Sea-bottoms, 

on  Earth,  118. 

on  Mars,  118. 
Sea-level,  lowering  of,  121. 
Seas, 

the  earliest   home  of   mundane  life, 
41-42,  68. 

sedimentary  formations  dependent  on, 
43-44- 

inland,  121. 

drying  up  of,  123. 
Seasons, 

absence  of,  when  Earth  was  screened 
from  Sun,  51. 

advent  registered  in  changed  vegeta- 
tion, 71-72. 

long  on  Mars,  78. 

two,  of  Martian  growth,  183. 

relative  length  of,  determined,   113. 
Seaweeds,  45. 
Sedimentary  formations, 

fourth  evolutionary  stage,  12,  43. 

dependent  on  seas,  43,  44. 
Silicon,  38. 
Silurian  era,  45. 

Sky,  light  of,  by  day,  Notes  246. 
Sladen  expedition,  121. 
Slipher,  E.  C.,  Notes  279. 
Slipher,  V.  M.,  138,  Notes  256,  276. 
Slope  exposure,  102. 
Snow, 

of  polar  caps,  180. 

precipitation  of,  Notes  269-270. 
Snow-fall, 

in  Alaska,  141. 

on  Mars,  141. 
Solar  constant,  Notes  242. 
Solar  system, 

catastrophic  origin  of,  3. 

moment  of  momentum  of,  3,  Notes  219. 

meteoric  constitution  of,  5. 

meteorites,  members  of,  Notes   225. 
Species, 

supplanting  of  others  by  one,  206. 

unification  of,  207. 
Spectroscope,  the,  137. 
Spectrum,  energy  of,  Notes  242. 


288 


INDEX 


Stefan,  86. 

Struggle  for  existence,  204-205. 

Struve,  Hermann,  200. 

Summer, 

the  life  season,  90,  95,  96. 

investigation   on,    by   Dr.    Merriam, 
90-91,  95. 

bearing  upon  the  habitability  of  Mars, 

96. 
Sun, 

paleozoic,  49,  Notes  232-235. 

causes  seasons,  50. 

not  the  source  of  Earth's  early  heat, 
So. 

becomes  dominant,  70. 

first  let  in  by  Earth's  cooling,  70. 
Sun  stage,  the,  12. 
Surface  features  of  Mars  visible,  73. 

permanent  in  place,  77. 

changes  in,  80. 

smoother  than  Earth's,  186-187. 
Surface  heat, 

of  Moon,  87,  88. 

of  Mars,   89. 

their  air  compatible  with  great,  87. 
Surface  of  equilibrium,  201. 

Teisserenc  de  Bort,  Notes  247. 
Telluric  lines  in  spectrum,  137. 
Temperature, 

of  Mars,  89. 

due  to  the  Sun,  83. 

new  determination  of,   83-86. 

in  summer  and  winter,  87. 

mean,  Notes  240-255. 

within  which  life  can  exist,  39,  90. 
Terraqueous  stage,  12. 

Earth  in,  12,  13. 

Terrestrial  stage,  12;  Mars  in,  12. 
Tertiary  era,  71. 

Thirst,  planetary  mode  of  death,  207. 
Tibetan  tablelands, 

effect  on  climate,  99. 
Tidal  effects,  Notes  270. 
Tokio,  size  of,  214. 
Trees,  deciduous, 

first  appearance  of,  71. 
Triassic  period, 

(new  red  sandstone),  70. 
Trilobites,  45. 
Trivium  Charontis,  149. 
Tropic  of  Cancer,  125. 
Tropic  of  Capricorn,  125. 


Twilight, 

short  on  Mars,  78. 

Upper  Silurian  era, 
insects  found  in,  46. 

Variation,  spontaneous, 

the  motive  principle  of  life,  53. 

each  planet  sets  a  different  stage  for, 

64-65. 
Vegetal  life, 

effect  of  plateaux  upon,  99,  102. 

blue-green  and   ochre   color  suggest 
it,  106. 

on  peaks,  103. 
Vegetal  quickening,  177. 
Vegetation, 

luxuriance  of,  in  paleozoic  times,  51. 

explains  behavior  of  canals,  177. 

sprouting  time,  on  Earth,  180. 

speed  of,  181. 

spread  of,  181. 

sprouting  time  on  Mars,  182. 
Venus,  178. 

markings  on,  192-193. 

rotary  retardation  of,  207. 

visibility  of  fine  lines,  Notes  269-279. 
Vernal  quickening,   178. 
Very,  Professor,  87,  88,  Notes  242,  243. 
Vogel,  138. 
Volcanic  phenomena, 

proportional  to  mass  of  planet,  16. 

occur  where  crust  is  most  permeable, 
1 6. 

Water, 

in  proportion  to  mass  of  planet,  31. 

essential  to  life,  39. 

boiling  points  of,  on  Earth  and  Mars, 
39,  Notes  231-232. 

specific  heat  of,  51. 

relative  amounts  on  Earth  and  Mars, 
141. 

the  answer  to  the  riddle,  198-203. 

of  polar  caps,  204. 

loss  of  supply,  208. 
Water-vapor, 

in  the  air  of  Mars,  103,  135,  139. 

effect  on  spectrum,  Notes  248. 

Year,  length  of  Martian,  78. 
Zones,  area  of,  163. 


QB     Lowell-Mars  as  the  abode  of  life. 
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